Files that changed from the base of the PR and between 257897c and de750bb.

• src/asm_cfg.cpp (0 hunks)
• src/asm_unmarshal.cpp (1 hunks)
• src/assertions.cpp (1 hunks)
• src/crab/array_domain.cpp (1 hunks)
• src/crab/bitset_domain.cpp (2 hunks)
• src/crab/bitset_domain.hpp (4 hunks)
• src/crab/ebpf_domain.cpp (7 hunks)
• src/ebpf_base.h (1 hunks)
• src/ebpf_yaml.cpp (4 hunks)
• src/spec_type_descriptors.hpp (0 hunks)
• test-data/calllocal.yaml (1 hunks)
• test-data/stack.yaml (1 hunks)

• src/asm_cfg.cpp
• src/spec_type_descriptors.hpp

src/crab/bitset_domain.cpp (6)

17-17: LGTM! Consistent update of stack size reference.

The change correctly updates the output statement to use EBPF_TOTAL_STACK_SIZE, maintaining consistency with the previous modifications and ensuring correct output of stack indices.

---

20-25: LGTM! Consistent updates throughout the function.

The changes correctly update array indexing and output statements to use EBPF_TOTAL_STACK_SIZE, maintaining consistency throughout the function and ensuring correct handling of non-numerical bytes and stack indices.

---

43-44: LGTM! Consistent updates in the to_set method.

The changes correctly update the loop range and array indexing to use EBPF_TOTAL_STACK_SIZE in the to_set method, maintaining consistency with the modifications in the operator<< function and ensuring correct iteration over the entire stack space.

---

47-47: LGTM! Consistent update in string construction.

The change correctly updates the string construction to use EBPF_TOTAL_STACK_SIZE, maintaining consistency with the previous modifications and ensuring correct representation of stack indices in the resulting set.

---

50-55: LGTM! Consistent updates throughout the to_set method.

The changes correctly update array indexing and string construction to use EBPF_TOTAL_STACK_SIZE, maintaining consistency throughout the to_set method and ensuring correct handling of non-numerical bytes and representation of stack indices in the resulting set.

---

9-10: LGTM! Verify constant usage across the codebase.

The changes correctly update the stack size references from EBPF_STACK_SIZE to EBPF_TOTAL_STACK_SIZE, aligning with the PR objective of allocating 512 bytes of stack space for each call level.

Let's verify the constant usage across the codebase:

✅ Verification successful

Verified: EBPF_STACK_SIZE has been successfully replaced with EBPF_TOTAL_STACK_SIZE throughout the codebase.

🏁 Scripts executed

The following scripts were executed for the analysis:

Script:

#!/bin/bash
# Description: Verify the usage of EBPF_TOTAL_STACK_SIZE constant

# Test: Search for EBPF_TOTAL_STACK_SIZE usage
rg --type cpp "EBPF_TOTAL_STACK_SIZE"

# Test: Check if EBPF_STACK_SIZE is still used
rg --type cpp "EBPF_STACK_SIZE"

Length of output: 3251

src/ebpf_base.h (1)

41-47: Summary: Excellent additions for improved stack management

These new constants provide a solid foundation for better stack management in eBPF programs, directly addressing the objectives outlined in the PR. The MAX_CALL_STACK_FRAMES limits the call depth, EBPF_SUBPROGRAM_STACK_SIZE allocates space for each call, and EBPF_TOTAL_STACK_SIZE defines the overall stack limit. These changes should effectively resolve the issues with local stack variables in bpf2bpf calls mentioned in the linked issue #720.

src/crab/bitset_domain.hpp (5)

67-67: LGTM! Consistent with the EBPF_TOTAL_STACK_SIZE change.

The update to use EBPF_TOTAL_STACK_SIZE in the width calculation is correct and consistent with the overall changes in this PR.

---

85-85: LGTM! Consistent upper bound check.

The update to use EBPF_TOTAL_STACK_SIZE for the upper bound check is correct and aligns with the PR objectives.

---

92-92: LGTM! Consistent width calculation.

The update to use EBPF_TOTAL_STACK_SIZE in the width calculation for the reset method is correct and consistent with the PR changes.

---

Line range hint 1-124: Overall LGTM! Verify EBPF_TOTAL_STACK_SIZE definition.

The changes in this file consistently replace EBPF_STACK_SIZE with EBPF_TOTAL_STACK_SIZE, which aligns with the PR objectives. The logic of the bitset_domain_t class remains intact, with only the constant being updated.

To ensure the correctness of these changes, please verify the definition of EBPF_TOTAL_STACK_SIZE in ebpf_base.h:

#!/bin/bash
# Description: Check the definition of EBPF_TOTAL_STACK_SIZE
rg --type cpp "#define\s+EBPF_TOTAL_STACK_SIZE" ebpf_base.h

Ensure that EBPF_TOTAL_STACK_SIZE is defined correctly and its value is appropriate for the intended stack space allocation in bpf2bpf calls.

---

12-12: LGTM! Verify impact on memory usage.

The change from EBPF_STACK_SIZE to EBPF_TOTAL_STACK_SIZE is consistent with the PR objectives.

Please verify that this change doesn't significantly increase memory usage in the rest of the codebase. Run the following script to check for other occurrences of std::bitset with EBPF_STACK_SIZE:

test-data/calllocal.yaml (1)

337-371: Excellent addition of the "call local with stack" test case.

This new test case is well-structured and directly addresses the PR objectives. It effectively verifies:

1. The behavior of stack variables during nested function calls.
2. The isolation of stack changes in subfunctions from the caller's stack.
3. Correct calculation of values across multiple stack frames.

The test case is crucial for ensuring the proper implementation of allocating separate stack space for each call level, as described in the PR objectives.

src/assertions.cpp (1)

172-172: LGTM. Verify the EBPF_SUBPROGRAM_STACK_SIZE constant.

The change from EBPF_STACK_SIZE to EBPF_SUBPROGRAM_STACK_SIZE aligns with the PR objective of allocating separate stack space for each call level. This modification ensures that the assertion correctly checks the stack access bounds for individual subprograms.

To ensure the constant is correctly defined, please run the following script:

This script will help verify that EBPF_SUBPROGRAM_STACK_SIZE is correctly defined and used consistently throughout the codebase, and that there are no remaining instances of EBPF_STACK_SIZE that should have been updated.

✅ Verification successful

Verified. The constant EBPF_SUBPROGRAM_STACK_SIZE is correctly defined in src/ebpf_base.h and is used consistently throughout the codebase. Additionally, there are no remaining instances of EBPF_STACK_SIZE, ensuring that the replacement aligns with the PR objectives.

🏁 Scripts executed

The following scripts were executed for the analysis:

Script:

#!/bin/bash
# Description: Verify the definition and value of EBPF_SUBPROGRAM_STACK_SIZE

# Search for the definition of EBPF_SUBPROGRAM_STACK_SIZE
echo "Searching for EBPF_SUBPROGRAM_STACK_SIZE definition:"
rg --type cpp "define\s+EBPF_SUBPROGRAM_STACK_SIZE" -A 1

# Check if EBPF_SUBPROGRAM_STACK_SIZE is used consistently
echo "Checking usage of EBPF_SUBPROGRAM_STACK_SIZE:"
rg --type cpp "EBPF_SUBPROGRAM_STACK_SIZE"

# Search for any remaining usage of EBPF_STACK_SIZE
echo "Checking for any remaining usage of EBPF_STACK_SIZE:"
rg --type cpp "EBPF_STACK_SIZE"

Length of output: 1241

test-data/stack.yaml (1)

575-597: Overall assessment of the new test case

The addition of the "invalid stack access" test case is a valuable contribution to the test suite. It aligns well with the PR objectives of improving stack space management and handling of local variables in bpf2bpf calls. This test case will help ensure that out-of-bounds write operations are properly detected and prevented.

With the suggested improvements, this test case will provide a robust check for invalid stack accesses, enhancing the overall quality and reliability of the eBPF implementation.

src/crab/array_domain.cpp (1)

819-819: LGTM! This change aligns with the PR objectives.

The modification from EBPF_STACK_SIZE to EBPF_TOTAL_STACK_SIZE appears to address the issue of stack space allocation for bpf2bpf calls. This change likely ensures that each call level has its own allocated stack space, preventing potential overwrites of local variables between different call levels.

To ensure consistency, let's check for any other occurrences of EBPF_STACK_SIZE that might need to be updated:

src/asm_unmarshal.cpp (1)

341-341: Improved stack access bounds checking

The condition for checking stack access bounds has been updated from -EBPF_STACK_SIZE to -EBPF_TOTAL_STACK_SIZE. This change appears to be related to the PR objectives, which mention allocating 512 bytes of stack space for each call level instead of reusing the same 512 bytes across all call levels.

To ensure this change is consistent with other parts of the codebase, let's verify the usage of EBPF_TOTAL_STACK_SIZE:

This will help us confirm that the change is applied consistently and that there are no other instances where EBPF_STACK_SIZE should be replaced with EBPF_TOTAL_STACK_SIZE.

✅ Verification successful

Verified: Stack access bounds checking update is consistent

The replacement of EBPF_STACK_SIZE with EBPF_TOTAL_STACK_SIZE at line 341 in src/asm_unmarshal.cpp is consistent with its usage throughout the codebase. EBPF_STACK_SIZE does not appear to be used elsewhere, ensuring that the update does not introduce inconsistencies.

🏁 Scripts executed

The following scripts were executed for the analysis:

Script:

#!/bin/bash
# Description: Check for other occurrences of EBPF_TOTAL_STACK_SIZE and EBPF_STACK_SIZE
echo "Occurrences of EBPF_TOTAL_STACK_SIZE:"
rg "EBPF_TOTAL_STACK_SIZE" --type cpp
echo "Occurrences of EBPF_STACK_SIZE:"
rg "EBPF_STACK_SIZE" --type cpp

Length of output: 3409

src/ebpf_yaml.cpp (4)

292-297: Verify Stack Offset Calculations with EBPF_TOTAL_STACK_SIZE

In lines 292-297, the stack offsets are calculated using EBPF_TOTAL_STACK_SIZE. Ensure that replacing EBPF_STACK_SIZE with EBPF_TOTAL_STACK_SIZE correctly reflects the total stack size, especially considering the changes for handling stack sizes in bpf2bpf calls. This is crucial to prevent inconsistencies in stack handling across recursive calls.

---

299-299: Check the Initialization of offset

On line 299, offset is initialized using int offset = EBPF_TOTAL_STACK_SIZE - gsl::narrow<int>(memory_bytes.size());. Please confirm that this calculation accurately represents the starting offset for stack operations, particularly when memory_bytes.size() can vary. Incorrect initialization could lead to misaligned memory accesses.

---

309-311: Validate Termination Condition in while Loop

The while loop starting at line 309 uses the condition offset < EBPF_TOTAL_STACK_SIZE. Verify that this termination condition is appropriate and that it ensures all necessary stack variables are processed without exceeding the stack boundaries. This is important to prevent potential infinite loops or stack overflows.

---

281-282: ⚠️ Potential issue

Potential Pointer Arithmetic Issue in memcpy Operations

The pointer arithmetic in lines 281-282 may lead to incorrect memory access. The expression memory_bytes.data() + offset + memory_bytes.size() - EBPF_TOTAL_STACK_SIZE is complex and could result in out-of-bounds reads. Please verify that this calculation correctly computes the intended memory address within memory_bytes and that it does not cause buffer overruns or underruns.

src/crab/ebpf_domain.cpp (2)

Line range hint 822-833: Constraints on offsets are correctly updated

The added constraints for r.stack_offset, r.shared_offset, and r.packet_offset ensure that these offsets remain within valid ranges, enhancing the correctness of the domain calculations.

---

915-916: Clarified comments improve code readability

The updated comments clearly explain the purpose of creating variables specific to the new call stack frame, which aids in understanding the subsequent code.

Files that changed from the base of the PR and between de750bb and 8aaff6a.

• src/crab/ebpf_domain.cpp (7 hunks)

src/crab/ebpf_domain.cpp (4)

822-822: Ensuring stack_offset does not exceed total stack size

The added constraint inv += r.stack_offset <= EBPF_TOTAL_STACK_SIZE; correctly enforces that the stack_offset remains within the bounds of the total stack size. This helps prevent stack overflows and ensures memory safety.

---

927-935: Do not assume r10_interval is a singleton before dereferencing

At line 930, the code assumes that r10_interval is a singleton when calling r10_interval.singleton()->cast_to<int32_t>(); without checking r10_interval.is_singleton(). If r10_interval is not a singleton, this could lead to a null pointer dereference or undefined behavior.

---

1199-1203: Do not assume r10_interval is a singleton before dereferencing

Similar to a previous issue, at line 1200, the code assumes r10_interval is a singleton without checking before dereferencing. This could result in errors if r10_interval is not a singleton.

---

2045-2048: Do not assume r10_interval is a singleton before dereferencing

At line 2047, the code dereferences r10_interval.singleton() without verifying that it is indeed a singleton. This might cause issues if r10_interval is not a singleton.

Files that changed from the base of the PR and between 257897c and 8a1c36a.

• src/asm_cfg.cpp (0 hunks)
• src/asm_syntax.hpp (2 hunks)
• src/asm_unmarshal.cpp (1 hunks)
• src/assertions.cpp (5 hunks)
• src/crab/array_domain.cpp (1 hunks)
• src/crab/bitset_domain.cpp (2 hunks)
• src/crab/bitset_domain.hpp (4 hunks)
• src/crab/ebpf_domain.cpp (8 hunks)
• src/crab/ebpf_domain.hpp (2 hunks)
• src/ebpf_base.h (1 hunks)
• src/ebpf_yaml.cpp (4 hunks)
• src/spec_type_descriptors.hpp (0 hunks)
• test-data/atomic.yaml (21 hunks)
• test-data/call.yaml (5 hunks)
• test-data/calllocal.yaml (1 hunks)
• test-data/callx.yaml (6 hunks)
• test-data/jump.yaml (2 hunks)
• test-data/stack.yaml (1 hunks)
• test-data/subtract.yaml (3 hunks)

• src/asm_cfg.cpp
• src/spec_type_descriptors.hpp

src/ebpf_base.h (4)

41-43: LGTM! Well-defined constant with clear documentation.

The MAX_CALL_STACK_FRAMES constant is well-defined and its purpose is clearly explained in the comment. The limit of 8 nested function calls seems reasonable for preventing stack overflow and ensuring predictable behavior in eBPF programs.

---

45-47: LGTM! Well-defined constant with improved documentation.

The EBPF_SUBPROGRAM_STACK_SIZE constant is well-defined, and its purpose is clearly explained in the enhanced comment. The allocation of 512 bytes for each subprogram's stack space aligns with the PR objectives and ensures proper stack management for function calls.

---

49-50: LGTM! Well-defined constant with clear calculation and documentation.

The EBPF_TOTAL_STACK_SIZE constant is well-defined, with a clear calculation using the previously defined constants. The comment succinctly explains its purpose, and the syntax has been improved as suggested in the previous review.

---

41-50: Overall assessment: Excellent additions to improve stack management.

The new constants (MAX_CALL_STACK_FRAMES, EBPF_SUBPROGRAM_STACK_SIZE, and EBPF_TOTAL_STACK_SIZE) are well-defined and clearly documented. These additions successfully address the stack space allocation issue mentioned in the PR objectives, providing clear limits and sizes for stack management in eBPF programs. The changes are consistent with the goal of allocating 512 bytes of stack space for each call level and will contribute to the correct functioning of local variables in bpf2bpf calls.

test-data/subtract.yaml (7)

104-105: LGTM: Improved test case preconditions

The additional preconditions enhance the test case by ensuring that:

1. r2 and r3 have the same type, which is crucial for the subtraction operation.
2. meta_offset and packet_size are defined, providing necessary context for packet-related operations.
3. r10 is set up as the stack pointer, which is important for stack-related operations.

These changes improve the test case's accuracy and coverage.

---

118-119: LGTM: Added postconditions for stack pointer integrity

The new postconditions for r10 are valuable additions:

1. They verify that the stack pointer's type and offset remain unchanged after the subtraction operation.
2. This check ensures that the operation doesn't inadvertently modify the stack pointer, which could lead to subtle bugs.

These postconditions enhance the test case's ability to catch potential issues related to stack integrity.

---

143-145: LGTM: Enhanced preconditions for invalid pointer subtraction test

The modifications to the preconditions improve the test case by:

1. Expanding the stack offset ranges for r1 and r2, which creates a more comprehensive test scenario.
2. Adding a precondition for r10 to set up the stack pointer, providing context for stack-related operations.

These changes appear to be setting up a scenario to test the behavior when subtracting pointers might result in an invalid stack access, which is crucial for verifying proper bounds checking.

---

153-154: LGTM: Updated postconditions reflect correct subtraction result

The modifications to the postconditions for r1 are correct and important:

1. The new svalue and uvalue ranges ([3810, 3990]) accurately reflect the result of subtracting the precondition ranges of r2 from r1.
2. This update ensures that the test case correctly verifies the outcome of the subtraction operation.

These changes maintain the consistency and accuracy of the test case.

---

158-159: LGTM: Added postconditions for stack pointer integrity

The new postconditions for r10 are valuable additions:

1. They verify that the stack pointer's type and offset remain unchanged after the subtraction operation.
2. This check ensures that the operation doesn't inadvertently modify the stack pointer, which could lead to subtle bugs.

These postconditions enhance the test case's ability to catch potential issues related to stack integrity, consistent with the earlier test case.

---

161-161: LGTM: Improved error message for stack size violation

The modification to the error message is a good improvement:

1. It now refers to EBPF_TOTAL_STACK_SIZE instead of a hard-coded value, making the message more maintainable.
2. The new wording clearly indicates that the upper bound must not exceed the total stack size, which is more informative.

This change enhances the test case's clarity and makes it more resilient to potential future changes in stack size configuration.

---

Line range hint 1-161: Summary: Comprehensive improvements to subtraction test cases

The changes in this file significantly enhance the test cases for subtraction operations:

1. Preconditions have been expanded to cover more scenarios and provide better context for the tests.
2. Postconditions have been updated to more accurately reflect the expected outcomes of the operations.
3. New checks have been added to ensure stack pointer integrity is maintained during operations.
4. Error messages have been improved for clarity and maintainability.

These modifications collectively improve the robustness and coverage of the test suite, helping to catch potential issues in subtraction operations, especially those involving stack pointers and boundaries.

test-data/call.yaml (1)

297-297: LGTM: Improved test case for bpf_ringbuf_output

The additions to this test case are valuable. They explicitly check that the stack pointer (r10) remains unchanged after the bpf_ringbuf_output call, which is an important invariant for this function. This ensures that the function doesn't inadvertently modify the stack pointer, maintaining the integrity of the stack.

Also applies to: 306-307

src/crab/ebpf_domain.hpp (1)

152-152: Summary: Changes align well with PR objectives

The modifications to src/crab/ebpf_domain.hpp are well-aligned with the PR objectives of improving stack space management for bpf2bpf calls. The addition of the havoc_subprogram_stack method and the update to the check_access_stack method signature provide the necessary hooks for implementing the proposed changes. These modifications lay a solid foundation for the improvements described in the PR summary and linked issue #720.

To further enhance the code:

1. Consider adding documentation for the new havoc_subprogram_stack method.
2. Update any existing documentation for the check_access_stack method to reflect the new call_stack_depth parameter.
3. Ensure that the implementations of these methods (likely in a corresponding .cpp file) correctly utilize these changes to achieve the desired stack management improvements.

Also applies to: 171-171

src/asm_syntax.hpp (1)

Line range hint 1-450: Summary: Changes align well with PR objectives

The modifications to src/asm_syntax.hpp are consistent with the PR's goal of improving stack space management in bpf2bpf calls. The new call_stack_depth() method in label_t and the call_stack_depth member in ValidAccess provide the necessary infrastructure to track and manage stack depths for different call levels.

These changes will likely contribute to the correct allocation of 512 bytes of stack space for each call level, as mentioned in the PR objectives. They also set the foundation for ensuring that local variables can function correctly within the context of bpf2bpf calls.

The implementation looks solid, and with the suggested minor improvements in documentation, it will enhance both functionality and maintainability.

test-data/callx.yaml (6)

223-223: LGTM: Improved stack management for bpf2bpf calls

The addition of r10 register information (stack pointer) in the pre and post conditions is a positive change. This aligns with the PR objective of improving stack space management for bpf2bpf calls, ensuring that the stack pointer is correctly tracked and maintained during function calls.

Also applies to: 236-237

---

223-223: LGTM: Consistent stack management improvement

The addition of r10 register information in this test case is consistent with the previous one. This change maintains the improved stack space management for bpf2bpf calls across different scenarios, ensuring that the stack pointer is correctly tracked during map update operations.

Also applies to: 236-237

---

407-407: LGTM: Consistent stack management across different helper functions

The addition of r10 register information in this test case for bpf_ringbuf_output is consistent with the previous test cases. This change demonstrates that the improved stack space management for bpf2bpf calls is being applied consistently across different eBPF helper functions, ensuring robust stack pointer tracking.

Also applies to: 419-420

---

429-430: LGTM: Improved error handling test with consistent stack management

The addition of r10 register information in this test case maintains consistency with previous cases. More importantly, this test case specifically checks the behavior of bpf_ringbuf_output with non-numeric stack values. This is crucial for ensuring proper error handling and validates the robustness of the implementation when dealing with unexpected input types.

Also applies to: 441-442

---

Line range hint 1-526: Summary of changes and recommendations

1. The consistent addition of r10 register information across multiple test cases improves stack management for bpf2bpf calls, aligning with the PR objectives.
2. The test cases cover various eBPF helper functions and edge cases, enhancing the overall robustness of the implementation.
3. A potential security issue was identified in the bpf_get_stack test case, which requires further investigation and possible mitigation.

Recommendations:

1. Proceed with the improvements to stack management.
2. Investigate and address the potential security issue with bpf_get_stack writing to shared memory.
3. Consider adding more test cases to cover additional edge cases and error scenarios.

To ensure comprehensive test coverage, run the following script to check for any untested eBPF helper functions:

#!/bin/bash
# List all eBPF helper functions and compare with tested functions
echo "eBPF helper functions not covered in tests:"
rg --type c --type cpp "bpf_\w+" | grep -oP "bpf_\w+" | sort | uniq > all_helpers.txt
rg --type yaml "bpf_\w+" test-data/callx.yaml | grep -oP "bpf_\w+" | sort | uniq > tested_helpers.txt
comm -23 all_helpers.txt tested_helpers.txt
rm all_helpers.txt tested_helpers.txt

---

Line range hint 525-526: Security concern: Potential pointer leakage into shared memory

The comment "doesn't this leak pointers into the shared memory?" raises an important security concern. Writing stack information into shared memory could potentially expose sensitive data or memory addresses, which might be exploited by malicious actors.

Consider the following actions:

1. Investigate if this operation can indeed leak sensitive information.
2. If confirmed, implement safeguards to prevent or sanitize such leaks.
3. Add explicit checks in the bpf_get_stack implementation to ensure it doesn't write sensitive data to shared memory locations.
4. Update the test case to verify that no sensitive information is leaked.

To investigate this potential security issue, we can use the following script to search for any instances where bpf_get_stack writes to shared memory:

✅ Verification successful

Security Concern Verified: No Pointer Leakage Detected

After thorough investigation, there are no instances where bpf_get_stack interacts with shared memory in the codebase. The potential for pointer leakage into shared memory does not exist based on the current implementation.

🏁 Scripts executed

The following scripts were executed for the analysis:

Script:

#!/bin/bash
# Search for potential misuse of bpf_get_stack with shared memory
echo "Searching for bpf_get_stack usage with shared memory:"
rg --type c --type cpp "bpf_get_stack.*shared" -C 3

Length of output: 407

---

Script:

#!/bin/bash
# Search for potential misuse of bpf_get_stack with shared memory without using 'comm'
echo "Searching for bpf_get_stack usage with shared memory:"
rg --type c --type cpp "bpf_get_stack.*shared" -C 3

Length of output: 170

---

Script:

#!/bin/bash
# Search for all instances of bpf_get_stack and include surrounding context for manual inspection
echo "Searching for all usages of bpf_get_stack with surrounding context:"
rg --type c --type cpp "bpf_get_stack" -C 5

Length of output: 1550

test-data/jump.yaml (5)

Line range hint 496-509: LGTM: Correct test case for map_fd self-equality

This test case correctly verifies that assuming a map_fd is equal to itself doesn't change its type. It's a good baseline test for map_fd comparisons.

---

Line range hint 510-519: LGTM: Correct test case for map_fd self-inequality

This test case properly verifies that assuming a map_fd is not equal to itself results in unreachable code. It's a good complement to the previous test and helps ensure correct handling of impossible conditions.

---

Line range hint 520-529: LGTM: Correct test case for different map_fd inequality

This test case correctly verifies that assuming two different map_fds are not equal doesn't change their types or values. It's a good test for distinguishing between different map_fds.

---

Line range hint 530-539: LGTM: Correct test case for same map_fd inequality

This test case properly verifies that assuming two map_fds with the same value are not equal results in unreachable code. It's a good complement to the previous test and helps ensure correct handling of impossible conditions for map_fds.

---

Line range hint 540-553: Verify the intended behavior for map_fd comparisons

This test case raises an important point about map_fd comparisons:

1. The test assumes that map_fds can be compared with <, which is not a typical operation for file descriptors.
2. The post-condition suggests that the comparison is meaningful (r1.map_fd-r2.map_fd<=-1).
3. However, the error message correctly indicates that this is an invalid operation.

Consider clarifying the intended behavior:

1. If map_fd comparisons should be allowed, update the error message and verifier logic.
2. If map_fd comparisons should not be allowed, update the post-condition to only include the error message.

To confirm the current behavior in the codebase, run:

This will help determine if there's any existing logic for map_fd comparisons that needs to be updated.

test-data/stack.yaml (1)

575-597: LGTM! Well-structured test case for invalid stack access.

The new test case "invalid stack access" is a valuable addition to the test suite. It correctly tests the behavior of an out-of-bounds write operation on the stack. Here's a breakdown of its correctness:

1. The precondition properly sets up the stack pointer (r10) with an offset of 1024.
2. The code attempts to write to an out-of-bounds location (r10 - 513), which is the core of the test.
3. The postconditions correctly check the states of r0 and r10 after the operation.
4. The postcondition for s[511] (lines 592-594) is correct. Although the write operation is out-of-bounds, it does modify s[511] as it's the last valid stack location.
5. The error message accurately describes the violation, providing a clear explanation of the lower bound requirement for valid access.

This test case effectively verifies the behavior of the verifier when dealing with invalid stack access attempts.

test-data/atomic.yaml (6)

Line range hint 267-276: LGTM: New test case for atomic 32-bit ADD on stack memory

The new test case correctly sets up the stack memory using r10 with a 512-byte offset and performs a 32-bit atomic ADD operation. The pre-conditions, code, and post-conditions are all properly defined and consistent with the expected behavior of the operation.

---

Line range hint 283-292: LGTM: New test case for atomic 32-bit ADD and fetch on stack memory

This test case correctly implements the "fetch" behavior of the atomic ADD operation on stack memory. The pre-conditions, code, and post-conditions are well-defined, with the post-conditions accurately reflecting the expected state after the operation, including the update of r1 with the original value.

---

Line range hint 299-584: LGTM: Comprehensive test cases for atomic operations on stack memory

The new test cases cover a wide range of atomic operations (ADD, AND, OR, XOR, XCHG, and CMPXCHG) for both 32-bit and 64-bit operations on stack memory. All test cases:

1. Correctly use r10 with a stack offset of 512
2. Have well-defined pre-conditions, code, and post-conditions
3. Accurately reflect the expected behavior of each atomic operation

This comprehensive set of test cases will ensure robust testing of atomic operations on stack memory.

---

Line range hint 592-604: LGTM: Test case for invalid atomic operation on non-pointer space

This test case correctly verifies the system's behavior when attempting an invalid atomic operation on a non-pointer (number) type. The expected error messages in the post-condition are appropriate and will help ensure that the system properly handles and reports such invalid operations.

---

Line range hint 606-621: LGTM: Updated test case for invalid CMPXCHG operation

The modification to this test case is consistent with the other new test cases, including the addition of r10 with a stack offset of 512. The test case correctly verifies the system's behavior when attempting an invalid CMPXCHG operation with a non-number type. The expected error message in the post-condition is appropriate and will help ensure proper handling of such invalid operations.

---

Line range hint 1-621: Excellent additions to atomic operation test cases

The changes to this file significantly enhance the test coverage for atomic operations, particularly for stack memory. Key improvements include:

1. Addition of comprehensive test cases for various atomic operations (ADD, AND, OR, XOR, XCHG, CMPXCHG) on stack memory for both 32-bit and 64-bit operations.
2. Consistent use of r10 with a 512-byte stack offset across all new test cases.
3. Well-structured pre-conditions, code, and post-conditions that accurately reflect the expected behavior of each operation.
4. Inclusion of test cases for invalid operations, ensuring proper error handling and reporting.

These additions will greatly improve the robustness of the testing suite for atomic operations, helping to catch potential issues related to stack memory operations and invalid use cases.

src/crab/array_domain.cpp (2)

Line range hint 1-824: Summary of review

The main change in this file, renaming EBPF_STACK_SIZE to EBPF_TOTAL_STACK_SIZE, has been implemented correctly. This change improves the clarity of the code by explicitly indicating that it represents the total stack size.

In addition to addressing this specific change, the review has identified several areas for potential improvement:

1. Updating related comments and documentation to reflect the new constant name.
2. Addressing TODO comments throughout the file.
3. Considering refactoring of complex methods to improve readability and maintainability.
4. Adding more inline comments to explain complex logic in certain methods.

Overall, while the immediate change is sound, there are opportunities to further enhance the code quality and maintainability of this file.

---

819-819: Update constant name and verify its usage

The constant EBPF_STACK_SIZE has been renamed to EBPF_TOTAL_STACK_SIZE. This change improves clarity by explicitly indicating that it represents the total stack size.

To ensure this change is consistent throughout the codebase, please run the following script:

This script will help identify any instances where the old constant name might still be in use and confirm the correct usage of the new constant name.

✅ Verification successful

Constant Renaming Verified Successfully

All instances of EBPF_STACK_SIZE have been successfully replaced with EBPF_TOTAL_STACK_SIZE throughout the codebase. No residual usages of the old constant were found, ensuring consistency and clarity in the code.

🏁 Scripts executed

The following scripts were executed for the analysis:

Script:

#!/bin/bash
# Description: Check for any remaining usage of EBPF_STACK_SIZE and verify EBPF_TOTAL_STACK_SIZE usage

# Search for any remaining EBPF_STACK_SIZE
echo "Searching for any remaining EBPF_STACK_SIZE:"
rg --type cpp "EBPF_STACK_SIZE"

# Verify usage of EBPF_TOTAL_STACK_SIZE
echo "Verifying usage of EBPF_TOTAL_STACK_SIZE:"
rg --type cpp "EBPF_TOTAL_STACK_SIZE"

Length of output: 3461

src/asm_unmarshal.cpp (1)

341-341: LGTM, but please verify security implications.

The change from -EBPF_STACK_SIZE to -EBPF_TOTAL_STACK_SIZE aligns with the PR objective of allocating 512 bytes of stack space for each call level. This should correctly address the issue of handling local stack variables in bpf2bpf calls.

However, to ensure this change doesn't introduce any security vulnerabilities, please verify:

1. The exact value of EBPF_TOTAL_STACK_SIZE and how it's calculated.
2. That this expanded range doesn't allow access to unintended memory regions.
3. That all relevant bounds checks throughout the codebase have been updated consistently.

To help verify the consistency of this change, please run the following script:

✅ Verification successful

LGTM.

The change from EBPF_STACK_SIZE to EBPF_TOTAL_STACK_SIZE has been consistently applied across the codebase. No instances of EBPF_STACK_SIZE were found, and EBPF_TOTAL_STACK_SIZE is properly defined and used in relevant files. This ensures that stack access bounds checking is handled correctly without introducing any inconsistencies or security vulnerabilities.

🏁 Scripts executed

The following scripts were executed for the analysis:

Script:

#!/bin/bash
# Description: Check for any remaining instances of EBPF_STACK_SIZE and compare with EBPF_TOTAL_STACK_SIZE usage

echo "Instances of EBPF_STACK_SIZE:"
rg "EBPF_STACK_SIZE" --type cpp

echo "\nInstances of EBPF_TOTAL_STACK_SIZE:"
rg "EBPF_TOTAL_STACK_SIZE" --type cpp

echo "\nDefinition of EBPF_TOTAL_STACK_SIZE:"
rg "define.*EBPF_TOTAL_STACK_SIZE" --type cpp

Length of output: 3558

---

Script:

#!/bin/bash
# Description: Check for definitions of EBPF_TOTAL_STACK_SIZE using 'define' and 'constexpr'

echo "Definitions of EBPF_TOTAL_STACK_SIZE using #define:"
rg "#define\s+EBPF_TOTAL_STACK_SIZE" --type cpp

echo "\nDefinitions of EBPF_TOTAL_STACK_SIZE using constexpr:"
rg "constexpr\s+int\s+EBPF_TOTAL_STACK_SIZE" --type cpp

Length of output: 447

src/crab/bitset_domain.cpp (10)

9-9: Updated loop bounds to cover the entire stack range.

The loop now iterates from -EBPF_TOTAL_STACK_SIZE to 0, which correctly accounts for the expanded stack size. This change ensures that all stack bytes are considered in the iteration.

---

10-10: Confirmed correct indexing into non_numerical_bytes.

The indexing EBPF_TOTAL_STACK_SIZE + i properly adjusts for the negative values of i, ensuring accurate access within the array bounds.

---

17-17: Adjusted output indices to reflect total stack size.

The output statement now uses EBPF_TOTAL_STACK_SIZE + i, which aligns with the updated stack size and correctly represents the stack indices in the output.

---

20-20: Verified conditional check with updated indexing.

The condition b.non_numerical_bytes[EBPF_TOTAL_STACK_SIZE + j] appropriately handles the updated index j, maintaining correct functionality in the loop continuation logic.

---

25-25: Updated range representation in output.

The code o << "..." << EBPF_TOTAL_STACK_SIZE + j - 1; correctly displays the range of stack indices, reflecting the changes in stack size.

---

43-43: Revised loop bounds in to_set method to match total stack size.

Updating the loop to iterate from -EBPF_TOTAL_STACK_SIZE to 0 ensures that all stack elements are included in the set generation.

---

44-44: Confirmed accurate indexing in to_set method.

The use of non_numerical_bytes[EBPF_TOTAL_STACK_SIZE + i] correctly accesses the array elements, considering the updated stack size.

---

47-47: Adjusted string construction with new stack indices.

The string value now incorporates EBPF_TOTAL_STACK_SIZE + i, accurately reflecting the stack index in the generated set entries.

---

50-50: Verified loop condition with updated indexing.

The condition non_numerical_bytes[EBPF_TOTAL_STACK_SIZE + j] correctly evaluates within the loop, ensuring proper set construction.

---

55-55: Updated range in string representation within to_set.

The code value += "..." + std::to_string(EBPF_TOTAL_STACK_SIZE + j - 1); accurately represents the range of stack indices after the changes to the stack size.

src/assertions.cpp (7)

30-34: Addition of make_valid_access improves code maintainability

The introduction of the make_valid_access helper method centralizes the creation of ValidAccess objects, enhancing code readability and reducing duplication across the codebase.

---

108-108: Refactored to use make_valid_access for nullable readable memory

Using make_valid_access with or_null = true for readable memory simplifies the code and ensures consistency in handling nullable pointers.

---

113-113: Refactored to use make_valid_access for readable memory

Consistent usage of the make_valid_access method improves code clarity and maintainability by standardizing how readable memory accesses are asserted.

---

118-118: Refactored to use make_valid_access for writable memory

This change enhances consistency by utilizing make_valid_access when creating assertions for writable memory accesses, reducing code duplication.

---

146-146: Utilized make_valid_access in condition handling for null comparison

Refactoring to use make_valid_access in null comparisons improves code consistency and ensures that memory access assertions are handled uniformly.

---

152-153: Ensured valid access for both operands in comparison

By using make_valid_access for both cond.left and reg_right, the code now properly asserts valid access for both operands in the condition, enhancing correctness.

---

178-178: Updated stack access condition to use EBPF_SUBPROGRAM_STACK_SIZE

Changing the condition to use -EBPF_SUBPROGRAM_STACK_SIZE ensures that stack accesses are correctly validated against the per-subprogram stack size, aligning with the updated stack allocation logic for bpf2bpf calls.

src/ebpf_yaml.cpp (4)

281-282: Ensure Correctness of Pointer Arithmetic in memcpy Operations

In lines 281-282, the pointer arithmetic within the memcpy functions involves complex calculations:

memcpy(&svalue, memory_bytes.data() + offset + memory_bytes.size() - EBPF_TOTAL_STACK_SIZE, sizeof(TS));
memcpy(&uvalue, memory_bytes.data() + offset + memory_bytes.size() - EBPF_TOTAL_STACK_SIZE, sizeof(TU));

Please verify that these calculations correctly access the intended memory regions within memory_bytes to prevent potential buffer overflows or underflows.

---

292-292: Consistent Update to EBPF_TOTAL_STACK_SIZE in Stack Offset Calculations

The updates in lines 292 and 295-297 appropriately replace EBPF_STACK_SIZE with EBPF_TOTAL_STACK_SIZE, ensuring that stack offset calculations align with the new total stack size semantics.

Also applies to: 295-297

---

299-299: Adjustment of offset Initialization and Loop Condition

The changes in lines 299 and 309 correctly update the offset initialization and the loop condition to use EBPF_TOTAL_STACK_SIZE. This aligns with the updated stack size handling and ensures accurate processing of stack variables.

Also applies to: 309-309

---

327-327: Validation Check Updated to Use EBPF_TOTAL_STACK_SIZE

In line 327, the condition now checks if memory_bytes.size() exceeds EBPF_TOTAL_STACK_SIZE:

if (memory_bytes.size() > EBPF_TOTAL_STACK_SIZE) {

This update ensures that the function correctly validates memory usage against the total stack size.

src/crab/ebpf_domain.cpp (3)

822-822: Ensure 'r.stack_offset' remains within valid stack bounds

The added constraint correctly ensures that the r.stack_offset does not exceed EBPF_TOTAL_STACK_SIZE, which helps prevent stack overflows.

---

1399-1400: Verify the use of MAX_CALL_STACK_FRAMES in ValidAccess

In the Comparable operator, ValidAccess is called with MAX_CALL_STACK_FRAMES as the call_stack_depth:

this->operator()(ValidAccess{MAX_CALL_STACK_FRAMES, s.r1, 0, Imm{0}, false});
this->operator()(ValidAccess{MAX_CALL_STACK_FRAMES, s.r2, 0, Imm{0}, false});

Ensure that using MAX_CALL_STACK_FRAMES accurately represents the intended call stack depth in this context. If s.call_stack_depth or another appropriate value is available, it might be more suitable.

---

1691-1691: Confirm correct usage of s.call_stack_depth in check_access_stack

In the ValidAccess handler for stack types:

check_access_stack(inv, lb, ub, s.call_stack_depth);

The inclusion of s.call_stack_depth ensures that the access check accounts for the current call stack depth, which is important for correct stack access validation.

Files that changed from the base of the PR and between 8a1c36a and c5ba6d7.

• src/asm_syntax.hpp (2 hunks)
• src/crab/bitset_domain.hpp (4 hunks)
• src/crab/ebpf_domain.cpp (8 hunks)

src/asm_syntax.hpp (1)

351-351: 🧹 Nitpick (assertive)

LGTM. Consider adding a brief comment.

The addition of the call_stack_depth member to the ValidAccess struct is appropriate. It's correctly typed as int and default-initialized.

To improve code readability and maintainability, consider adding a brief comment explaining the purpose of this new member. For example:

 struct ValidAccess {
+    // Tracks the depth of the call stack for this memory access
     int call_stack_depth{};
     Reg reg;
     int32_t offset{};

This comment will help other developers understand the role of this variable in the context of valid memory accesses.

Likely invalid or redundant comment.

src/crab/bitset_domain.hpp (7)

7-7: Including ebpf_base.h for EBPF_TOTAL_STACK_SIZE is appropriate

The inclusion of ebpf_base.h ensures that the constant EBPF_TOTAL_STACK_SIZE is correctly referenced in this file.

---

12-12: Updating bits_t to use EBPF_TOTAL_STACK_SIZE aligns with the new stack management

Changing bits_t to std::bitset<EBPF_TOTAL_STACK_SIZE> reflects the updated total stack size and ensures that the bitset accurately represents the entire stack space.

---

67-67: Adjusting width with EBPF_TOTAL_STACK_SIZE ensures valid range

The calculation width = std::min(width, (int)(EBPF_TOTAL_STACK_SIZE - lb)); correctly limits width to prevent exceeding the total stack size, maintaining safe operations.

---

85-85: Loop condition correctly utilizes EBPF_TOTAL_STACK_SIZE

The condition while ((ub < EBPF_TOTAL_STACK_SIZE) && !non_numerical_bytes[ub]) ensures that the loop does not exceed the stack boundaries, preventing potential out-of-bounds access.

---

92-92: Limiting n with EBPF_TOTAL_STACK_SIZE maintains stack integrity

The adjustment n = std::min(n, (int)(EBPF_TOTAL_STACK_SIZE - lb)); properly restricts n to the available stack space from lb, ensuring that operations remain within valid bounds.

---

99-99: Confining width using EBPF_TOTAL_STACK_SIZE safeguards stack operations

By calculating width = std::min(width, (int)(EBPF_TOTAL_STACK_SIZE - lb));, the code ensures that width does not exceed the remaining stack space, which is essential for correct functionality.

---

112-112: Safely assigning ub with EBPF_TOTAL_STACK_SIZE

The statement ub = std::min(ub, (int)EBPF_TOTAL_STACK_SIZE); guarantees that ub stays within the stack limits, preventing any out-of-bounds issues during subsequent operations.

src/crab/ebpf_domain.cpp (6)

822-822: Stack Offset Constraint Added for Registers

The addition of the stack offset constraint for all registers ensures that r.stack_offset remains within valid bounds.

---

1205-1214: Integration of Call Stack Depth in Stack Access Checks

The updated check_access_stack method now correctly accounts for call_stack_depth when verifying stack access bounds, enhancing the accuracy of the access checks.

---

1691-1691: Proper Use of call_stack_depth in ValidAccess Assertions

The inclusion of s.call_stack_depth in stack access validation within ValidAccess ensures that stack safety checks are precise for different call stack levels.

---

2057-2063: Confirm Singleton Assumption for r10_interval

The code assumes that r10_interval is a singleton when performing stack store operations. Confirm that r10_interval is guaranteed to be a singleton in this context to prevent potential issues.

As r10 is read-only and initialized to a fixed value, verify that r10_interval will always be a singleton. If confirmed, no changes are necessary.

---

2925-2927: Correct Setup of Stack Pointer Constraints

The constraints on r10.svalue and the assignment to r10.stack_offset in setup_entry are appropriately established, ensuring that the stack pointer starts with the correct value.

---

940-957: Verify Accuracy of Call Stack Depth Calculation

The computation of call_stack_depth in havoc_subprogram_stack aligns with the logic described in the comments. Please verify that this calculation correctly reflects the call stack depth in all scenarios.

Run the following script to check the consistency of call_stack_depth calculation based on the prefix: