On Tue, Sep 03, 2019 at 02:39:27PM -0300, James Almer wrote: > On 9/3/2019 8:13 AM, Michael Niedermayer wrote: > > On Mon, Sep 02, 2019 at 09:40:47PM -0300, James Almer wrote: > >> On 9/2/2019 9:14 PM, Michael Niedermayer wrote: > >>> Fixes: OOM > >>> Fixes: > >>> 16627/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APE_fuzzer-5638059583864832 > >>> > >>> Found-by: continuous fuzzing process > >>> https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > >>> Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > >>> --- > >>> libavcodec/apedec.c | 3 +++ > >>> 1 file changed, 3 insertions(+) > >>> > >>> diff --git a/libavcodec/apedec.c b/libavcodec/apedec.c > >>> index e218f7c043..774ce18531 100644 > >>> --- a/libavcodec/apedec.c > >>> +++ b/libavcodec/apedec.c > >>> @@ -1475,6 +1475,9 @@ static int ape_decode_frame(AVCodecContext *avctx, > >>> void *data, > >>> return AVERROR_INVALIDDATA; > >>> } > >>> > >>> + if (nblocks * (int64_t)avctx->channels > avctx->max_samples) > >>> + return AVERROR(EINVAL); > >>> + > >> > >> Shouldn't this be checked in ff_get_buffer()? Same as max_pixels, but > >> checking "frame->nb_samples > avctx->max_samples" instead or > >> width/height. Otherwise it will barely be used. > > > > you are correct, it should be checked in *get_buffer somewhere too. > > But the offending allocation occurs before any *get_buffer calls so > > this check here is what is neccessary and sufficient for this specific > > bug > > If the allocation you're talking about is > https://git.videolan.org/?p=ffmpeg.git;a=blob;f=libavcodec/apedec.c;h=490b11b94e0b1666f18248b2b247c874fed6e0bc;hb=HEAD#l1500 > then you could just move it (and the five lines that follow it) right > below the ff_get_buffer() call.
will apply with these changes and some more to reset the incorrect samples in case of ff_get_buffer failure thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety -- Benjamin Franklin
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