| Message ID | 20200922083314.1467-1-michael@niedermayer.cc |
|---|---|
| State | Accepted |
| Commit | ee33fecb62c6dabcfdb9199d7a5b8575b758f1d9 |
| Headers | show |
| Series | [FFmpeg-devel] avcodec/mpeg12dec: Limit maximum A53 CC size | expand |
| Context | Check | Description |
|---|---|---|
| andriy/default | pending | |
| andriy/make | success | Make finished |
| andriy/make_fate | success | Make fate finished |
On Tue, Sep 22, 2020 at 10:33:14AM +0200, Michael Niedermayer wrote: > This is more than 10 times the size of the largest i found. And also alot more > than our encoder could handle (our encoder is limited to max 31) > Without any limit megabyte+ sized blocks can be reallocated millions of times. > Sadly the SCTE-20 spec does not seem to contain any hard limit directly, so this limit here > is arbitrary > > Fixes: Timeout (25sec -> 152ms) > Fixes: 25714/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEG2VIDEO_fuzzer-5713633336885248 > > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> > --- > libavcodec/mpeg12dec.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) will apply [...]
diff --git a/libavcodec/mpeg12dec.c b/libavcodec/mpeg12dec.c index ab470187a1..5884c6fd17 100644 --- a/libavcodec/mpeg12dec.c +++ b/libavcodec/mpeg12dec.c @@ -50,6 +50,8 @@ #include "version.h" #include "xvmc_internal.h" +#define A53_MAX_CC_COUNT 2000 + typedef struct Mpeg1Context { MpegEncContext mpeg_enc_ctx; int mpeg_enc_ctx_allocated; /* true if decoding context allocated */ @@ -2246,7 +2248,7 @@ static int mpeg_decode_a53_cc(AVCodecContext *avctx, * UINT64_C(3)); int ret; - if (new_size > INT_MAX) + if (new_size > 3*A53_MAX_CC_COUNT) return AVERROR(EINVAL); ret = av_buffer_realloc(&s1->a53_buf_ref, new_size); @@ -2269,7 +2271,7 @@ static int mpeg_decode_a53_cc(AVCodecContext *avctx, int old_size = s1->a53_buf_ref ? s1->a53_buf_ref->size : 0; const uint64_t new_size = (old_size + cc_count * UINT64_C(3)); - if (new_size > INT_MAX) + if (new_size > 3*A53_MAX_CC_COUNT) return AVERROR(EINVAL); ret = av_buffer_realloc(&s1->a53_buf_ref, new_size); @@ -2339,7 +2341,7 @@ static int mpeg_decode_a53_cc(AVCodecContext *avctx, int old_size = s1->a53_buf_ref ? s1->a53_buf_ref->size : 0; const uint64_t new_size = (old_size + cc_count * UINT64_C(6)); - if (new_size > INT_MAX) + if (new_size > 3*A53_MAX_CC_COUNT) return AVERROR(EINVAL); ret = av_buffer_realloc(&s1->a53_buf_ref, new_size);
This is more than 10 times the size of the largest i found. And also alot more than our encoder could handle (our encoder is limited to max 31) Without any limit megabyte+ sized blocks can be reallocated millions of times. Sadly the SCTE-20 spec does not seem to contain any hard limit directly, so this limit here is arbitrary Fixes: Timeout (25sec -> 152ms) Fixes: 25714/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEG2VIDEO_fuzzer-5713633336885248 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> --- libavcodec/mpeg12dec.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)