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avcodec/dirac_arith: Treat overread as error

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Fixes: Timeout
Fixes: 11663/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DIRAC_fuzzer-5636791864918016

Before:Executed clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DIRAC_fuzzer-5636791864918016 in 26006 ms
After: Executed clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DIRAC_fuzzer-5636791864918016 in 106 ms

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2019-01-08 23:40:54 +01:00
parent 6ed3d0e01c
commit 51978aefe8
2 changed files with 5 additions and 0 deletions
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1
libavcodec/dirac_arith.c
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@ -116,6 +116,7 @@ void ff_dirac_init_arith_decoder(DiracArith *c, GetBitContext *gb, int length)
c->counter = -16; c->counter = -16;
c->range = 0xffff; c->range = 0xffff;
c->error = 0; c->error = 0;
c->overread= 0;
for (i = 0; i < DIRAC_CTX_COUNT; i++) for (i = 0; i < DIRAC_CTX_COUNT; i++)
c->contexts[i] = 0x8000; c->contexts[i] = 0x8000;

4
libavcodec/dirac_arith.h
View File

@ -82,6 +82,7 @@ typedef struct {
uint16_t contexts[DIRAC_CTX_COUNT]; uint16_t contexts[DIRAC_CTX_COUNT];
int error; int error;
int overread;
} DiracArith; } DiracArith;
extern const uint8_t ff_dirac_next_ctx[DIRAC_CTX_COUNT]; extern const uint8_t ff_dirac_next_ctx[DIRAC_CTX_COUNT];
@ -119,6 +120,9 @@ static inline void refill(DiracArith *c)
new |= 0xff00; new |= 0xff00;
c->bytestream = c->bytestream_end; c->bytestream = c->bytestream_end;
c->overread ++;
if (c->overread > 4)
c->error = AVERROR_INVALIDDATA;
} }
c->low += new << counter; c->low += new << counter;