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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 13:36:37 +0100 |
| commit | 512354191328c559fcff56070dab897ee2a1b4c1 (patch) | |
| tree | 6ee331569b219e498ac6c8c37093bf4960e07295 | |
| parent | 01f9540320279954b2764645ab7136847d53d89f (diff) | |
| download | ffmpeg-512354191328c559fcff56070dab897ee2a1b4c1.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 | 23 |
1 files changed, 14 insertions, 9 deletions
diff --git a/libavcodec/h264_sei.c b/libavcodec/h264_sei.c index 5995a8efec..776ce57d46 100644 --- a/libavcodec/h264_sei.c +++ b/libavcodec/h264_sei.c @@ -165,17 +165,22 @@ int ff_h264_decode_sei(H264Context *h){ MpegEncContext * const s = &h->s; while (get_bits_left(&s->gb) > 16) { - int size, type; + int type = 0; + int size = 0; + int last = 0; - type=0; - do{ - type+= show_bits(&s->gb, 8); - }while(get_bits(&s->gb, 8) == 255); + while (get_bits_left(&s->gb) >= 8 && + (last = get_bits(&s->gb, 8)) == 255) { + type += 255; + } + type += last; - size=0; - do{ - size+= show_bits(&s->gb, 8); - }while(get_bits(&s->gb, 8) == 255); + last = 0; + while (get_bits_left(&s->gb) >= 8 && + (last = get_bits(&s->gb, 8)) == 255) { + size += 255; + } + size += last; if (size > get_bits_left(&s->gb) / 8) { av_log(s->avctx, AV_LOG_ERROR, "SEI type %d truncated at %d\n", |