On 9/3/2017 10:49 AM, Ronald S. Bultje wrote: > Hi, > > On Sun, Sep 3, 2017 at 6:23 AM, Michael Niedermayer <mich...@niedermayer.cc> > wrote: > >> Fixes: Timeout >> Fixes: 3142/clusterfuzz-testcase-5007853163118592 >> >> Found-by: continuous fuzzing process https://github.com/google/oss- >> fuzz/tree/master/projects/ffmpeg >> Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> >> --- >> libavcodec/snowdec.c | 19 +++++++++++++++---- >> 1 file changed, 15 insertions(+), 4 deletions(-) >> >> diff --git a/libavcodec/snowdec.c b/libavcodec/snowdec.c >> index b74c468ce3..7e07857a44 100644 >> --- a/libavcodec/snowdec.c >> +++ b/libavcodec/snowdec.c >> @@ -183,13 +183,24 @@ static int decode_q_branch(SnowContext *s, int >> level, int x, int y){ >> int my_context= av_log2(2*FFABS(left->my - top->my)) + >> 0*av_log2(2*FFABS(tr->my - top->my)); >> >> type= get_rac(&s->c, &s->block_state[1 + left->type + top->type]) >> ? BLOCK_INTRA : 0; >> - >> if(type){ >> + int ld, cbd, crd; >> pred_mv(s, &mx, &my, 0, left, top, tr); >> - l += get_symbol(&s->c, &s->block_state[32], 1); >> + ld = get_symbol(&s->c, &s->block_state[32], 1); >> + if (ld < -255 || ld > 255) { >> + av_log(s->avctx, AV_LOG_ERROR, "Invalid ld %d\n", ld); >> + return AVERROR_INVALIDDATA; >> + } >> + l += ld; >> if (s->nb_planes > 2) { >> - cb+= get_symbol(&s->c, &s->block_state[64], 1); >> - cr+= get_symbol(&s->c, &s->block_state[96], 1); >> + cbd = get_symbol(&s->c, &s->block_state[64], 1); >> + crd = get_symbol(&s->c, &s->block_state[96], 1); >> + if (cbd < -255 || cbd > 255 || crd < -255 || crd > 255) { >> + av_log(s->avctx, AV_LOG_ERROR, "Invalid cbd %d, crd >> %d\n", cbd, crd); >> + return AVERROR_INVALIDDATA; >> + } >> + cb += cbd; >> + cr += crd; >> } > > > Can you elaborate on how these error messages, which are displayed to the > user by default, help the user resolve the > likely-to-occur-with-realworld-files situation where a validly-created file > doesn't play back? > > If any part of this sentence is not true, then why is there a message here? > > Ronald
Just go straight to the point, please. This fuzzing commit set in the past few months has been way more controversial than it has any right to. Michael: Don't add error messages at any level above debug if they are completely useless and unhelpful for non-developers. And Consider using ff_tlog() as well, so they don't become binary bloat on a non-debug build. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
