From: Erik de Castro Lopo <erikd@mega-nerd.com>

Date: Sun, 25 Aug 2019 07:24:47 +0000 (+1000)

Subject: libFLAC/bitreader.c: Fix shift invoking undefined behaviour

X-Git-Url: http://git.xiph.org/?p=flac.git;a=commitdiff_plain;h=09f47c00e18a77390acfc2e725564542756effaf

libFLAC/bitreader.c: Fix shift invoking undefined behaviour

Credit: Oss-Fuzz

Issue: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=16458

Testcase: fuzzer_decoder-5649174900506624

---

diff --git a/src/libFLAC/bitreader.c b/src/libFLAC/bitreader.c

index 90507435..62e11991 100644

--- a/src/libFLAC/bitreader.c

+++ b/src/libFLAC/bitreader.c

@@ -456,7 +456,7 @@ FLAC__bool FLAC__bitreader_read_raw_int32(FLAC__BitReader *br, FLAC__int32 *val,

{

FLAC__uint32 uval, mask;

/* OPT: inline raw uint32 code here, or make into a macro if possible in the .h file */

- if(!FLAC__bitreader_read_raw_uint32(br, &uval, bits))

+ if (bits < 1 || ! FLAC__bitreader_read_raw_uint32(br, &uval, bits))

return false;

/* sign-extend *val assuming it is currently bits wide. */

/* From: https://graphics.stanford.edu/~seander/bithacks.html#FixedSignExtend */