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avcodec/pnm: Check magic bytes directly without pnm_get()

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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 <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2019-08-01 20:04:15 +02:00
parent 77abf31453
commit 1a0f106232
1 changed files with 10 additions and 3 deletions
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13
libavcodec/pnm.c
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@ -22,6 +22,7 @@
#include <stdlib.h>
#include <string.h>
#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);