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Avoid reading outside of collection bounds #407

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Avoid reading outside of collection bounds #407

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Core: Avoid reading outside of collection bounds
mathiasbynens Aug 29, 2017
d85f4fb
Merge branch 'master' into avoid-reading-past-end-of-array
mathiasbynens Sep 11, 2017
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22 changes: 13 additions & 9 deletions dist/sizzle.js
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@
* Released under the MIT license
* https://js.foundation/
*
* Date: 2017-09-01
* Date: 2017-09-10
*/
(function( window ) {

Expand Down Expand Up @@ -656,7 +656,7 @@ setDocument = Sizzle.setDocument = function( node ) {
// getElementById is not reliable as a find shortcut
Expr.find["ID"] = function( id, context ) {
if ( typeof context.getElementById !== "undefined" && documentIsHTML ) {
var node, i, elems,
var node, i, elems, length,
elem = context.getElementById( id );

if ( elem ) {
Expand All @@ -669,8 +669,9 @@ setDocument = Sizzle.setDocument = function( node ) {

// Fall back on getElementsByName
elems = context.getElementsByName( id );
length = elems.length;
i = 0;
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This could moved to the body of a for right?

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Yes, for both i and length. However, i was already outside of the for, so I decided to follow the existing style.

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Oh, that because of the https://contribute.jquery.org/style-guide/js/#good-examples, i.e. it should be fine to put i to the body, as long its initialised on top of the scope, like we doing here – https://github.com/jquery/jquery/blob/692f9d4db30c9c6c4f6bc76005cf153586202fa6/src/effects.js#L614 :)

while ( (elem = elems[i++]) ) {
for ( ; i !== length && (elem = elems[ i ]) != null; i++ ) {
node = elem.getAttributeNode("id");
if ( node && node.value === id ) {
return [ elem ];
Expand Down Expand Up @@ -700,11 +701,12 @@ setDocument = Sizzle.setDocument = function( node ) {
tmp = [],
i = 0,
// By happy coincidence, a (broken) gEBTN appears on DocumentFragment nodes too
results = context.getElementsByTagName( tag );
results = context.getElementsByTagName( tag ),
length = results.length;

// Filter out possible comments
if ( tag === "*" ) {
while ( (elem = results[i++]) ) {
for ( ; i !== length && (elem = results[ i ]) != null; i++ ) {
if ( elem.nodeType === 1 ) {
tmp.push( elem );
}
Expand Down Expand Up @@ -1049,17 +1051,19 @@ Sizzle.uniqueSort = function( results ) {
var elem,
duplicates = [],
j = 0,
i = 0;
i = 0,
length = results.length;

// Unless we *know* we can detect duplicates, assume their presence
hasDuplicate = !support.detectDuplicates;
sortInput = !support.sortStable && results.slice( 0 );
results.sort( sortOrder );

if ( hasDuplicate ) {
while ( (elem = results[i++]) ) {
if ( elem === results[ i ] ) {
j = duplicates.push( i );
for ( ; i < length; i++ ) {
elem = results[ i ];
if ( i + 1 < length && elem === results[ i + 1 ] ) {
j = duplicates.push( i + 1 );
}
}
while ( j-- ) {
Expand Down
2 changes: 1 addition & 1 deletion dist/sizzle.min.map
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28 changes: 14 additions & 14 deletions package-lock.json
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20 changes: 12 additions & 8 deletions src/sizzle.js
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Original file line number Diff line number Diff line change
Expand Up @@ -656,7 +656,7 @@ setDocument = Sizzle.setDocument = function( node ) {
// getElementById is not reliable as a find shortcut
Expr.find["ID"] = function( id, context ) {
if ( typeof context.getElementById !== "undefined" && documentIsHTML ) {
var node, i, elems,
var node, i, elems, length,
elem = context.getElementById( id );

if ( elem ) {
Expand All @@ -669,8 +669,9 @@ setDocument = Sizzle.setDocument = function( node ) {

// Fall back on getElementsByName
elems = context.getElementsByName( id );
length = elems.length;
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@gibson042 gibson042 Aug 30, 2017 •
edited
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NodeList#length can be an element in IE<9 (and we should have a test where that is the case on this line). cf. f6e2fc5#diff-7d34356c0b7229dd5da8b6c7711b32b7R1733

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So, something like this?

if (typeof elem.length === 'number') {
  fastPath();
} else {
  slowPathForLegacyBrowsers();
}

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Yes, provided we can get it without excessive file size increase.

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example:

for ( ; i !== len && (elem = elems[i]) != null; i++ ) {

i = 0;
while ( (elem = elems[i++]) ) {
for ( ; i !== length && (elem = elems[ i ]) != null; i++ ) {
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This is probably not an issue, but I feel like i < length is safer.

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i < length would definitely be an issue, because length might be a DOM node in IE<9.

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makes sense.

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Perhaps we could put in a comment relating that as a reminder.

node = elem.getAttributeNode("id");
if ( node && node.value === id ) {
return [ elem ];
Expand Down Expand Up @@ -700,11 +701,12 @@ setDocument = Sizzle.setDocument = function( node ) {
tmp = [],
i = 0,
// By happy coincidence, a (broken) gEBTN appears on DocumentFragment nodes too
results = context.getElementsByTagName( tag );
results = context.getElementsByTagName( tag ),
length = results.length;
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Same problem here.

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Done.


// Filter out possible comments
if ( tag === "*" ) {
while ( (elem = results[i++]) ) {
for ( ; i !== length && (elem = results[ i ]) != null; i++ ) {
if ( elem.nodeType === 1 ) {
tmp.push( elem );
}
Expand Down Expand Up @@ -1049,17 +1051,19 @@ Sizzle.uniqueSort = function( results ) {
var elem,
duplicates = [],
j = 0,
i = 0;
i = 0,
length = results.length;
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Same problem here.

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Done.


// Unless we *know* we can detect duplicates, assume their presence
hasDuplicate = !support.detectDuplicates;
sortInput = !support.sortStable && results.slice( 0 );
results.sort( sortOrder );

if ( hasDuplicate ) {
while ( (elem = results[i++]) ) {
if ( elem === results[ i ] ) {
j = duplicates.push( i );
for ( ; i < length; i++ ) {
elem = results[ i ];
if ( i + 1 < length && elem === results[ i + 1 ] ) {
j = duplicates.push( i + 1 );
}
}
while ( j-- ) {
Expand Down