On Wed, Jun 19, 2019 at 03:59:47PM -0300, James Almer wrote: > On 6/19/2019 3:13 PM, Michael Niedermayer wrote: > > On Wed, Jun 19, 2019 at 12:54:25PM -0300, James Almer wrote: > >> On 6/19/2019 6:22 AM, Michael Niedermayer wrote: > >>> On Mon, Jun 17, 2019 at 07:55:45PM -0300, James Almer wrote: > >>>> On 6/17/2019 6:54 PM, Michael Niedermayer wrote: > >>>>> On Sun, Jun 16, 2019 at 11:10:43PM -0300, James Almer wrote: > >>>>>> On 6/13/2019 3:32 PM, Michael Niedermayer wrote: > >>>>>>> Fixes: signed integer overflow: -2147483648 - 1 cannot be represented > >>>>>>> in type 'int' > >>>>>>> Fixes: > >>>>>>> 14880/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_HEVC_fuzzer-5130977304641536 > >>>>>>> > >>>>>>> Found-by: continuous fuzzing process > >>>>>>> https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > >>>>>>> Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > >>>>>>> --- > >>>>>>> libavcodec/hevc_ps.c | 2 +- > >>>>>>> 1 file changed, 1 insertion(+), 1 deletion(-) > >>>>>>> > >>>>>>> diff --git a/libavcodec/hevc_ps.c b/libavcodec/hevc_ps.c > >>>>>>> index 80df417e4f..0ed6682bb4 100644 > >>>>>>> --- a/libavcodec/hevc_ps.c > >>>>>>> +++ b/libavcodec/hevc_ps.c > >>>>>>> @@ -1596,7 +1596,7 @@ int ff_hevc_decode_nal_pps(GetBitContext *gb, > >>>>>>> AVCodecContext *avctx, > >>>>>>> if (pps->num_tile_rows <= 0 || > >>>>>>> pps->num_tile_rows >= sps->height) { > >>>>>>> av_log(avctx, AV_LOG_ERROR, "num_tile_rows_minus1 out of > >>>>>>> range: %d\n", > >>>>>>> - pps->num_tile_rows - 1); > >>>>>>> + pps->num_tile_rows - 1U); > >>>>>> > >>>>>> The proper fix for this is making pps->num_tile_rows/cols unsigned. > >>> [...] > >>>>> > >>>>> is this here ok if num_tile_rows is 0 ? > >>>>> for (i = 0; i < pps->num_tile_rows - 1; i++) { (example line from > >>>>> ffmpeg git) > >>>>> > >>>>> i would guess nearly everyone wold say yes without having seen the > >>>>> discussion about the type. but of course if this is unsigned its not > >>>>> going to be safe with it being 0. > >>>> > >>>> pps->num_tile_rows is set to a value returned by "get_ue_golomb_long() + > >>>> 1", which will always be in the 1..UINT32_MAX range. It can't be 0, as > >>>> it would be a bug. Int is definitely not the right type for it. > >>> > >>> i dont think num_tile_rows of more than 2^31 (that is the negative when > >>> signed range) > >>> makes much sense but sure i can change it to unsigned if preferred. > >> > >> Of course it doesn't. In pretty much any sample it will be at least 1 > >> and at most 22, which is the max value allowed by hevc level 6.2 in > >> table A.6. Only if the stream reports an undefined level it could go up > >> to, if i'm reading this right, sps->ctb_height and not sps->height as > >> the decoder is currently checking. This means you can even replace > >> get_ue_golomb_long() for a get_ue_golomb(). That would also fix this. > >> > >> In any case, the bitstream value is unsigned, so the struct field should > >> be unsigned as well. Having it be signed and assigning it a value using > >> a function that potentially returns huge unsigned values introduced this > >> issue to being with, so instead of working around it using type > >> promotion, just make it follow the spec. > > > > what would be your feeling/oppinon about making the field uint16_t ? > > this would make it unsigned in the struct but avoid the problems with > > unsigned int ? > > That's fine. Could even make it uint8_t, like cbs_h265.h does. I'd also > change it to use get_ue_golomb() while at it. And please do it for both > rows and columns. Can be in separate patches if you want the rows one to > explicitly address the fuzzing testcase.
will do but this requires intermediate int, ill post a new patch get_ue_golomb() can return negative error codes. storing this in an 8bit variable would truncate the error code and could fold it into a valid value. [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB I have never wished to cater to the crowd; for what I know they do not approve, and what they approve I do not know. -- Epicurus
signature.asc
Description: PGP signature
_______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
