From 9d931ce6260c8d5ede80aedec48a68bfb7771c23 Mon Sep 17 00:00:00 2001
From: Martijn van Beurden <mvanb1@gmail.com>
Date: Wed, 19 Jun 2024 13:00:30 +0200
Subject: [PATCH] Make UTF-8 decoder more restrictive

Fixes https://github.com/xiph/flac/issues/706
---
 src/libFLAC/bitreader.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/src/libFLAC/bitreader.c b/src/libFLAC/bitreader.c
index 829b308e00..44bc4e89ed 100644
--- a/src/libFLAC/bitreader.c
+++ b/src/libFLAC/bitreader.c
@@ -939,23 +939,23 @@ FLAC__bool FLAC__bitreader_read_utf8_uint32(FLAC__BitReader *br, FLAC__uint32 *v
 		v = x;
 		i = 0;
 	}
-	else if(x & 0xC0 && !(x & 0x20)) { /* 110xxxxx */
+	else if((x & 0xE0) == 0xC0) { /* 110xxxxx */
 		v = x & 0x1F;
 		i = 1;
 	}
-	else if(x & 0xE0 && !(x & 0x10)) { /* 1110xxxx */
+	else if((x & 0xF0) == 0xE0) { /* 1110xxxx */
 		v = x & 0x0F;
 		i = 2;
 	}
-	else if(x & 0xF0 && !(x & 0x08)) { /* 11110xxx */
+	else if((x & 0xF8) == 0xF0) { /* 11110xxx */
 		v = x & 0x07;
 		i = 3;
 	}
-	else if(x & 0xF8 && !(x & 0x04)) { /* 111110xx */
+	else if((x & 0xFC) == 0xF8) { /* 111110xx */
 		v = x & 0x03;
 		i = 4;
 	}
-	else if(x & 0xFC && !(x & 0x02)) { /* 1111110x */
+	else if((x & 0xFE) == 0xFC) { /* 1111110x */
 		v = x & 0x01;
 		i = 5;
 	}
@@ -994,27 +994,27 @@ FLAC__bool FLAC__bitreader_read_utf8_uint64(FLAC__BitReader *br, FLAC__uint64 *v
 		v = x;
 		i = 0;
 	}
-	else if(x & 0xC0 && !(x & 0x20)) { /* 110xxxxx */
+	else if((x & 0xE0) == 0xC0) { /* 110xxxxx */
 		v = x & 0x1F;
 		i = 1;
 	}
-	else if(x & 0xE0 && !(x & 0x10)) { /* 1110xxxx */
+	else if((x & 0xF0) == 0xE0) { /* 1110xxxx */
 		v = x & 0x0F;
 		i = 2;
 	}
-	else if(x & 0xF0 && !(x & 0x08)) { /* 11110xxx */
+	else if((x & 0xF8) == 0xF0) { /* 11110xxx */
 		v = x & 0x07;
 		i = 3;
 	}
-	else if(x & 0xF8 && !(x & 0x04)) { /* 111110xx */
+	else if((x & 0xFC) == 0xF8) { /* 111110xx */
 		v = x & 0x03;
 		i = 4;
 	}
-	else if(x & 0xFC && !(x & 0x02)) { /* 1111110x */
+	else if((x & 0xFE) == 0xFC) { /* 1111110x */
 		v = x & 0x01;
 		i = 5;
 	}
-	else if(x & 0xFE && !(x & 0x01)) { /* 11111110 */
+	else if(x == 0xFE) { /* 11111110 */
 		v = 0;
 		i = 6;
 	}