| Message ID | 20230929232001.23197-4-michael@niedermayer.cc |
|---|---|
| State | New |
| Headers | show |
| Series | [FFmpeg-devel,1/6] avformat/avidec: support huge durations | expand |
| Context | Check | Description |
|---|---|---|
| yinshiyou/make_loongarch64 | success | Make finished |
| yinshiyou/make_fate_loongarch64 | success | Make fate finished |
| andriy/make_x86 | success | Make finished |
| andriy/make_fate_x86 | success | Make fate finished |
On 9/29/2023 8:19 PM, Michael Niedermayer wrote: > Fixes: signed integer overflow: 64 + 9223372036854775803 cannot be represented in type 'long long' > Fixes: 51896/clusterfuzz-testcase-minimized-ffmpeg_dem_CAF_fuzzer-6536881135550464 > > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> > --- > libavformat/cafdec.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/libavformat/cafdec.c b/libavformat/cafdec.c > index e92e3279fc6..0e50a3cfe68 100644 > --- a/libavformat/cafdec.c > +++ b/libavformat/cafdec.c > @@ -435,7 +435,7 @@ static int read_packet(AVFormatContext *s, AVPacket *pkt) > > /* don't read past end of data chunk */ > if (caf->data_size > 0) { > - left = (caf->data_start + caf->data_size) - avio_tell(pb); > + left = av_sat_add64(caf->data_start, caf->data_size) - avio_tell(pb); avio_tell(pb) here is guaranteed to be bigger than caf->data_start, which is the offset where the DATA chunk starts, so the result of this calculation will be <= INT64_MAX even if you don't saturate it and instead cast it to uint64_t. Nonetheless, if the DATA chunk ends at an offset that would not fit in an int64_t, then we can't parse it to begin with due to AVIOContext API limitations. Maybe we should just abort in read_header() if data_start + data_size > INT64_MAX, instead of pretending we can parse the file, invalid or not, by saturating values. > if (!left) > return AVERROR_EOF; > if (left < 0)
On Fri, Sep 29, 2023 at 08:41:23PM -0300, James Almer wrote: > On 9/29/2023 8:19 PM, Michael Niedermayer wrote: > > Fixes: signed integer overflow: 64 + 9223372036854775803 cannot be represented in type 'long long' > > Fixes: 51896/clusterfuzz-testcase-minimized-ffmpeg_dem_CAF_fuzzer-6536881135550464 > > > > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> > > --- > > libavformat/cafdec.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/libavformat/cafdec.c b/libavformat/cafdec.c > > index e92e3279fc6..0e50a3cfe68 100644 > > --- a/libavformat/cafdec.c > > +++ b/libavformat/cafdec.c > > @@ -435,7 +435,7 @@ static int read_packet(AVFormatContext *s, AVPacket *pkt) > > /* don't read past end of data chunk */ > > if (caf->data_size > 0) { > > - left = (caf->data_start + caf->data_size) - avio_tell(pb); > > + left = av_sat_add64(caf->data_start, caf->data_size) - avio_tell(pb); > > avio_tell(pb) here is guaranteed to be bigger than caf->data_start, which is > the offset where the DATA chunk starts, so the result of this calculation > will be <= INT64_MAX even if you don't saturate it and instead cast it to > uint64_t. Nonetheless, if the DATA chunk ends at an offset that would not > fit in an int64_t, then we can't parse it to begin with due to AVIOContext > API limitations. > > Maybe we should just abort in read_header() if data_start + data_size > > INT64_MAX, instead of pretending we can parse the file, invalid or not, by > saturating values. yes ill try that thx [...]
On Sat, Sep 30, 2023 at 06:32:07PM +0200, Michael Niedermayer wrote: > On Fri, Sep 29, 2023 at 08:41:23PM -0300, James Almer wrote: > > On 9/29/2023 8:19 PM, Michael Niedermayer wrote: > > > Fixes: signed integer overflow: 64 + 9223372036854775803 cannot be represented in type 'long long' > > > Fixes: 51896/clusterfuzz-testcase-minimized-ffmpeg_dem_CAF_fuzzer-6536881135550464 > > > > > > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > > > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> > > > --- > > > libavformat/cafdec.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/libavformat/cafdec.c b/libavformat/cafdec.c > > > index e92e3279fc6..0e50a3cfe68 100644 > > > --- a/libavformat/cafdec.c > > > +++ b/libavformat/cafdec.c > > > @@ -435,7 +435,7 @@ static int read_packet(AVFormatContext *s, AVPacket *pkt) > > > /* don't read past end of data chunk */ > > > if (caf->data_size > 0) { > > > - left = (caf->data_start + caf->data_size) - avio_tell(pb); > > > + left = av_sat_add64(caf->data_start, caf->data_size) - avio_tell(pb); > > > > avio_tell(pb) here is guaranteed to be bigger than caf->data_start, which is > > the offset where the DATA chunk starts, so the result of this calculation > > will be <= INT64_MAX even if you don't saturate it and instead cast it to > > uint64_t. Nonetheless, if the DATA chunk ends at an offset that would not > > fit in an int64_t, then we can't parse it to begin with due to AVIOContext > > API limitations. > > > > > Maybe we should just abort in read_header() if data_start + data_size > > > INT64_MAX, instead of pretending we can parse the file, invalid or not, by > > saturating values. > > yes ill try that ossfuzz moved the testcases all to another unrelated issues (62276) ill apply this as suggested with the check in read_header() below: diff --git a/libavformat/cafdec.c b/libavformat/cafdec.c index 72809fd1de2..07a2939a7a6 100644 --- a/libavformat/cafdec.c +++ b/libavformat/cafdec.c @@ -343,6 +343,9 @@ static int read_header(AVFormatContext *s) avio_skip(pb, 4); /* edit count */ caf->data_start = avio_tell(pb); caf->data_size = size < 0 ? -1 : size - 4; + if (caf->data_start < 0 || caf->data_size > INT64_MAX - caf->data_start) + return AVERROR_INVALIDDATA; + if (caf->data_size > 0 && (pb->seekable & AVIO_SEEKABLE_NORMAL)) avio_skip(pb, caf->data_size); found_data = 1; [...]
diff --git a/libavformat/cafdec.c b/libavformat/cafdec.c index e92e3279fc6..0e50a3cfe68 100644 --- a/libavformat/cafdec.c +++ b/libavformat/cafdec.c @@ -435,7 +435,7 @@ static int read_packet(AVFormatContext *s, AVPacket *pkt) /* don't read past end of data chunk */ if (caf->data_size > 0) { - left = (caf->data_start + caf->data_size) - avio_tell(pb); + left = av_sat_add64(caf->data_start, caf->data_size) - avio_tell(pb); if (!left) return AVERROR_EOF; if (left < 0)
Fixes: signed integer overflow: 64 + 9223372036854775803 cannot be represented in type 'long long' Fixes: 51896/clusterfuzz-testcase-minimized-ffmpeg_dem_CAF_fuzzer-6536881135550464 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> --- libavformat/cafdec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)