From 51978aefe8074cc3e020994f6b329387b2149cb8 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Tue, 8 Jan 2019 23:40:54 +0100 Subject: [PATCH] avcodec/dirac_arith: Treat overread as error 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 --- libavcodec/dirac_arith.c | 1 + libavcodec/dirac_arith.h | 4 ++++ 2 files changed, 5 insertions(+) diff --git a/libavcodec/dirac_arith.c b/libavcodec/dirac_arith.c index 1e6b964772..36142fe198 100644 --- a/libavcodec/dirac_arith.c +++ b/libavcodec/dirac_arith.c @@ -116,6 +116,7 @@ void ff_dirac_init_arith_decoder(DiracArith *c, GetBitContext *gb, int length) c->counter = -16; c->range = 0xffff; c->error = 0; + c->overread= 0; for (i = 0; i < DIRAC_CTX_COUNT; i++) c->contexts[i] = 0x8000; diff --git a/libavcodec/dirac_arith.h b/libavcodec/dirac_arith.h index efe30b79de..79526a7ca3 100644 --- a/libavcodec/dirac_arith.h +++ b/libavcodec/dirac_arith.h @@ -82,6 +82,7 @@ typedef struct { uint16_t contexts[DIRAC_CTX_COUNT]; int error; + int overread; } DiracArith; extern const uint8_t ff_dirac_next_ctx[DIRAC_CTX_COUNT]; @@ -119,6 +120,9 @@ static inline void refill(DiracArith *c) new |= 0xff00; c->bytestream = c->bytestream_end; + c->overread ++; + if (c->overread > 4) + c->error = AVERROR_INVALIDDATA; } c->low += new << counter;