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| author | Michael Niedermayer <michael@niedermayer.cc> | 2019-02-21 18:38:40 +0100 |
|---|---|---|
| committer | Michael Niedermayer <michael@niedermayer.cc> | 2019-02-23 22:48:35 +0100 |
| commit | 3f68948cb3036e239baa17d88b2f2ef1ecbb8f0c (patch) | |
| tree | 125a1d0de05a089aaa3c38e57f8836b9bd9827c1 | |
| parent | 177b40890c6de8c6896e0a1d4a631ea1ca89c044 (diff) | |
| download | ffmpeg-3f68948cb3036e239baa17d88b2f2ef1ecbb8f0c.tar.gz | |
avcodec/pnm: Avoid structure pointer dereferences in inner loop in pnm_get()
Improves speed from 5.4 to 4.2 seconds
Fixes: 13149/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PGM_fuzzer-5760833622114304
Fixes: 13166/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PGMYUV_fuzzer-5763216322330624
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Lauri Kasanen <cand@gmx.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
| -rw-r--r-- | libavcodec/pnm.c | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/libavcodec/pnm.c b/libavcodec/pnm.c index b06a6e81b5..17926f256f 100644 --- a/libavcodec/pnm.c +++ b/libavcodec/pnm.c @@ -36,13 +36,15 @@ static void pnm_get(PNMContext *sc, char *str, int buf_size) { char *s; int c; + uint8_t *bs = sc->bytestream; + const uint8_t *end = sc->bytestream_end; /* skip spaces and comments */ - while (sc->bytestream < sc->bytestream_end) { - c = *sc->bytestream++; + while (bs < end) { + c = *bs++; if (c == '#') { - while (c != '\n' && sc->bytestream < sc->bytestream_end) { - c = *sc->bytestream++; + while (c != '\n' && bs < end) { + c = *bs++; } } else if (!pnm_space(c)) { break; @@ -50,12 +52,13 @@ static void pnm_get(PNMContext *sc, char *str, int buf_size) } s = str; - while (sc->bytestream < sc->bytestream_end && !pnm_space(c)) { + while (bs < end && !pnm_space(c)) { if ((s - str) < buf_size - 1) *s++ = c; - c = *sc->bytestream++; + c = *bs++; } *s = '\0'; + sc->bytestream = bs; } int ff_pnm_decode_header(AVCodecContext *avctx, PNMContext * const s) |