[FFmpeg-devel] [PATCH] avcodec/v210dec: Fix alignment check for AVX2

[Michael Niedermayer]

On Sat, May 18, 2019 at 12:02:55PM +0200, James Darnley wrote:
> On 2019-05-18 09:39, Michael Niedermayer wrote:
> > Fixes: "null pointer dereference"
> > Fixes: 14551/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_V210_fuzzer-5088609952071680
> > 
> > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > ---
> >  libavcodec/v210dec.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/libavcodec/v210dec.c b/libavcodec/v210dec.c
> > index bc1e1d34ff..5a33d8c089 100644
> > --- a/libavcodec/v210dec.c
> > +++ b/libavcodec/v210dec.c
> > @@ -104,7 +104,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
> >          && avpkt->size - 64 >= stride * avctx->height)
> >          psrc += 64;
> >  
> > -    aligned_input = !((uintptr_t)psrc & 0xf) && !(stride & 0xf);
> > +    aligned_input = !((uintptr_t)psrc & 0x1f) && !(stride & 0x1f);
> >      if (aligned_input != s->aligned_input) {
> >          s->aligned_input = aligned_input;
> >          ff_v210dec_init(s);
> > 
> 
> Ah yes, that'll be needed after the recent addition of avx2.  LGTM and
> sorry.
> 

> I object to the commit message though because it isn't a "null pointer
> dereference" but if that is the error as reported by the tool then keep
> it as is.

yes, the tool(s) say things like "Null-dereference READ", "SEGV on unknown address 0x000000000000"

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Why not whip the teacher when the pupil misbehaves? -- Diogenes of Sinope
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 181 bytes
Desc: not available
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20190518/9eaa0335/attachment.sig>