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| author | Vittorio Giovara <vittorio.giovara@gmail.com> | 2014-07-30 19:33:36 +0100 |
|---|---|---|
| committer | Vittorio Giovara <vittorio.giovara@gmail.com> | 2014-08-01 13:08:32 +0100 |
| commit | 7ab551f9fd9a63586649a7df8790ddaeac55420f (patch) | |
| tree | 9deb5b67c81262226f850f9a19d884cadce4d7a7 | |
| parent | b2e059a1ffbdaaa985c6a7dcdd684fa034725238 (diff) | |
| download | ffmpeg-7ab551f9fd9a63586649a7df8790ddaeac55420f.tar.gz | |
h264: prevent theoretical infinite loop in SEI parsing
Properly address CVE-2011-3946 and parse bitstream as described in the spec.
CC: libav-stable@libav.org
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
| -rw-r--r-- | libavcodec/h264_sei.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/libavcodec/h264_sei.c b/libavcodec/h264_sei.c index 33230b7dfa..52ff2ff4bb 100644 --- a/libavcodec/h264_sei.c +++ b/libavcodec/h264_sei.c @@ -222,14 +222,20 @@ int ff_h264_decode_sei(H264Context *h) int size = 0; int type = 0; int ret = 0; + int last = 0; - do - type += show_bits(&h->gb, 8); - while (get_bits(&h->gb, 8) == 255); + while (get_bits_left(&h->gb) >= 8 && + (last = get_bits(&h->gb, 8)) == 255) { + type += 255; + } + type += last; - do - size += show_bits(&h->gb, 8); - while (get_bits(&h->gb, 8) == 255); + last = 0; + while (get_bits_left(&h->gb) >= 8 && + (last = get_bits(&h->gb, 8)) == 255) { + size += 255; + } + size += last; if (size > get_bits_left(&h->gb) / 8) { av_log(h->avctx, AV_LOG_ERROR, "SEI type %d truncated at %d\n", |