From 46cb61819d867961e8f2052a8f13bcf2027d484f Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Thu, 24 Jan 2013 04:17:58 +0100 Subject: [PATCH] gifdec: check that the last keyframe exists and has been successfully parsed. Prevents inconsistent state and null pointer dereference Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind Signed-off-by: Michael Niedermayer --- libavcodec/gifdec.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/libavcodec/gifdec.c b/libavcodec/gifdec.c index b0254decd1..51e8422951 100644 --- a/libavcodec/gifdec.c +++ b/libavcodec/gifdec.c @@ -75,6 +75,7 @@ typedef struct GifState { AVCodecContext *avctx; int keyframe; + int keyframe_ok; int trans_color; /**< color value that is used instead of transparent color */ } GifState; @@ -472,6 +473,7 @@ static int gif_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, A } if (s->keyframe) { + s->keyframe_ok = 0; if ((ret = gif_read_header1(s)) < 0) return ret; @@ -489,7 +491,13 @@ static int gif_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, A s->picture.pict_type = AV_PICTURE_TYPE_I; s->picture.key_frame = 1; + s->keyframe_ok = 1; } else { + if (!s->keyframe_ok) { + av_log(avctx, AV_LOG_ERROR, "cannot decode frame without keyframe\n"); + return AVERROR_INVALIDDATA; + } + if ((ret = avctx->reget_buffer(avctx, &s->picture)) < 0) { av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n"); return ret;