[FFmpeg-devel] [PATCH 2/2] avcodec/tiff: Fix integer overflows in left shift in init_image()

[Michael Niedermayer]

On Sat, Nov 24, 2018 at 11:46:36AM +0100, Tomas Härdin wrote:
> fre 2018-11-23 klockan 02:33 +0100 skrev Michael Niedermayer:
> > Fixes: left shift of 255 by 24 places cannot be represented in type 'int'
> > Fixes: 11377/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_TIFF_fuzzer-5694319101476864
> > 
> > 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/tiff.c | 10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> > 
> > diff --git a/libavcodec/tiff.c b/libavcodec/tiff.c
> > index 6271c937c3..64a3261fd9 100644
> > --- a/libavcodec/tiff.c
> > +++ b/libavcodec/tiff.c
> > @@ -706,7 +706,7 @@ static int init_image(TiffContext *s, ThreadFrame *frame)
> >          s->avctx->pix_fmt = s->palette_is_set ? AV_PIX_FMT_PAL8 : AV_PIX_FMT_GRAY8;
> >          break;
> >      case 10081:
> > -        switch (s->pattern[0] | (s->pattern[1] << 8) | (s->pattern[2] << 16) | (s->pattern[3] << 24)) {
> > +        switch (s->pattern[0] | (s->pattern[1] << 8) | (s->pattern[2] << 16) | ((unsigned)s->pattern[3] << 24)) {
> >          case 0x02010100:
> >              s->avctx->pix_fmt = AV_PIX_FMT_BAYER_RGGB8;
> >              break;
> > @@ -721,7 +721,7 @@ static int init_image(TiffContext *s, ThreadFrame *frame)
> >              break;
> >          default:
> >              av_log(s->avctx, AV_LOG_ERROR, "Unsupported Bayer pattern: 0x%X\n",
> > -                   s->pattern[0] | s->pattern[1] << 8 | s->pattern[2] << 16 | s->pattern[3] << 24);
> > +                   s->pattern[0] | s->pattern[1] << 8 | s->pattern[2] << 16 | (unsigned)s->pattern[3] << 24);
> >              return AVERROR_PATCHWELCOME;
> >          }
> >          break;
> > @@ -741,12 +741,12 @@ static int init_image(TiffContext *s, ThreadFrame *frame)
> >              break;
> >          default:
> >              av_log(s->avctx, AV_LOG_ERROR, "Unsupported Bayer pattern: 0x%X\n",
> > -                   s->pattern[0] | s->pattern[1] << 8 | s->pattern[2] << 16 | s->pattern[3] << 24);
> > +                   s->pattern[0] | s->pattern[1] << 8 | s->pattern[2] << 16 | (unsigned)s->pattern[3] << 24);
> >              return AVERROR_PATCHWELCOME;
> >          }
> >          break;
> >      case 10161:
> > -        switch (s->pattern[0] | s->pattern[1] << 8 | s->pattern[2] << 16 | s->pattern[3] << 24) {
> > +        switch (s->pattern[0] | s->pattern[1] << 8 | s->pattern[2] << 16 | (unsigned)s->pattern[3] << 24) {
> >          case 0x02010100:
> >              s->avctx->pix_fmt = s->le ? AV_PIX_FMT_BAYER_RGGB16LE : AV_PIX_FMT_BAYER_RGGB16BE;
> >              break;
> > @@ -761,7 +761,7 @@ static int init_image(TiffContext *s, ThreadFrame *frame)
> >              break;
> >          default:
> >              av_log(s->avctx, AV_LOG_ERROR, "Unsupported Bayer pattern: 0x%X\n",
> > -                   s->pattern[0] | s->pattern[1] << 8 | s->pattern[2] << 16 | s->pattern[3] << 24);
> > +                   s->pattern[0] | s->pattern[1] << 8 | s->pattern[2] << 16 | (unsigned)s->pattern[3] << 24);
> >              return AVERROR_PATCHWELCOME;
> >          }
> >          break;
> 
> So fixing undefined behavior mostly? A function might make this nicer
> looking, else there's not much to say

yes, indeed, ill post a patch doing that

thx

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

Freedom in capitalist society always remains about the same as it was in
ancient Greek republics: Freedom for slave owners. -- Vladimir Lenin
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