[FFmpeg-cvslog] avcodec/vc2enc: Fix overflows with storing large values

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Mon Jun 17 22:43:22 2024 +0200| [af9935835335cae1ae5a4ec7fc14c1b5e25c1f2d] | committer: Michael Niedermayer

avcodec/vc2enc: Fix overflows with storing large values

Fixes: left shift of 1431634944 by 2 places cannot be represented in type 'int'
Fixes: left shift of 1073741824 by 1 places cannot be represented in type 'int'
Fixes: 69061/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VC2_fuzzer-6325700826038272

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=af9935835335cae1ae5a4ec7fc14c1b5e25c1f2d
---

 libavcodec/vc2enc.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/libavcodec/vc2enc.c b/libavcodec/vc2enc.c
index 4ea836d9c9..7fa6ddc4ca 100644
--- a/libavcodec/vc2enc.c
+++ b/libavcodec/vc2enc.c
@@ -189,7 +189,9 @@ typedef struct VC2EncContext {
 static av_always_inline void put_vc2_ue_uint(PutBitContext *pb, uint32_t val)
 {
     int i;
-    int pbits = 0, bits = 0, topbit = 1, maxval = 1;
+    int bits = 0;
+    unsigned topbit = 1, maxval = 1;
+    uint64_t pbits = 0;
 
     if (!val++) {
         put_bits(pb, 1, 1);
@@ -206,12 +208,13 @@ static av_always_inline void put_vc2_ue_uint(PutBitContext *pb, uint32_t val)
 
     for (i = 0; i < bits; i++) {
         topbit >>= 1;
+        av_assert2(pbits <= UINT64_MAX>>3);
         pbits <<= 2;
         if (val & topbit)
             pbits |= 0x1;
     }
 
-    put_bits(pb, bits*2 + 1, (pbits << 1) | 1);
+    put_bits64(pb, bits*2 + 1, (pbits << 1) | 1);
 }
 
 static av_always_inline int count_vc2_ue_uint(uint32_t val)