From 1a0f106232f51cd20dc0ebab2c02de49ba26fa6b Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Thu, 1 Aug 2019 20:04:15 +0200 Subject: [PATCH] avcodec/pnm: Check magic bytes directly without pnm_get() Fixes: Timeout (10sec -> 30ms) (case 15089) Fixes: 15089/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PBM_fuzzer-5767535057698816 Fixes: 16001/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PGM_fuzzer-5199169645445120 Fixes: 16003/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PGMYUV_fuzzer-5076443270217728 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer --- libavcodec/pnm.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/libavcodec/pnm.c b/libavcodec/pnm.c index a9771710c2..cadfa7569e 100644 --- a/libavcodec/pnm.c +++ b/libavcodec/pnm.c @@ -22,6 +22,7 @@ #include #include +#include "libavutil/avassert.h" #include "libavutil/imgutils.h" #include "avcodec.h" #include "internal.h" @@ -68,9 +69,15 @@ int ff_pnm_decode_header(AVCodecContext *avctx, PNMContext * const s) int h, w, depth, maxval; int ret; - pnm_get(s, buf1, sizeof(buf1)); - if(buf1[0] != 'P') + if (s->bytestream_end - s->bytestream < 3 || + s->bytestream[0] != 'P' || + s->bytestream[1] < '1' || + s->bytestream[1] > '7') { + s->bytestream += s->bytestream_end > s->bytestream; + s->bytestream += s->bytestream_end > s->bytestream; return AVERROR_INVALIDDATA; + } + pnm_get(s, buf1, sizeof(buf1)); s->type= buf1[1]-'0'; if (s->type==1 || s->type==4) { @@ -152,7 +159,7 @@ int ff_pnm_decode_header(AVCodecContext *avctx, PNMContext * const s) } return 0; } else { - return AVERROR_INVALIDDATA; + av_assert0(0); } pnm_get(s, buf1, sizeof(buf1)); w = atoi(buf1);