On Thu, Jan 12, 2023 at 12:54:27AM +0100, Michael Niedermayer wrote: > Fixes: out of array access > Fixes: > 48567/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_EATGQ_fuzzer-6743211456724992 > > Found-by: continuous fuzzing process > https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg > Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > --- > libavcodec/eatgq.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/libavcodec/eatgq.c b/libavcodec/eatgq.c > index 89e9f20880..beb9f4d046 100644 > --- a/libavcodec/eatgq.c > +++ b/libavcodec/eatgq.c > @@ -56,7 +56,7 @@ static av_cold int tgq_decode_init(AVCodecContext *avctx) > return 0; > } > > -static void tgq_decode_block(TgqContext *s, int16_t block[64], GetBitContext > *gb) > +static int tgq_decode_block(TgqContext *s, int16_t block[64], GetBitContext > *gb) > { > const uint8_t *scantable = ff_zigzag_direct; > int i, j, value; > @@ -64,6 +64,8 @@ static void tgq_decode_block(TgqContext *s, int16_t > block[64], GetBitContext *gb > for (i = 1; i < 64;) { > switch (show_bits(gb, 3)) { > case 4: > + if (i >= 63) > + return AVERROR_INVALIDDATA; > block[scantable[i++]] = 0; > case 0: > block[scantable[i++]] = 0; > @@ -73,6 +75,8 @@ static void tgq_decode_block(TgqContext *s, int16_t > block[64], GetBitContext *gb > case 1: > skip_bits(gb, 2); > value = get_bits(gb, 6); > + if (value > 64 - i) > + return AVERROR_INVALIDDATA; > for (j = 0; j < value; j++) > block[scantable[i++]] = 0; > break; > @@ -100,6 +104,7 @@ static void tgq_decode_block(TgqContext *s, int16_t > block[64], GetBitContext *gb > } > } > block[0] += 128 << 4; > + return 0; > } > > static void tgq_idct_put_mb(TgqContext *s, int16_t (*block)[64], AVFrame > *frame, > -- > 2.17.1
Hi Michael, The return value of tgq_decode() is not checked anywhere. Need to add something like: - tgq_decode_block(s, s->block[i], &gb); + if ((ret = tgq_decode_block(s, s->block[i], &gb)) < 0) + return ret; (From earlier attempt at fixing this: https://patchwork.ffmpeg.org/project/ffmpeg/patch/1ab7c3994301a243fc64d59d6a08e3a2b364e411.1666774269.git.pr...@xvid.org/) -- Peter (A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)
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