[FFmpeg-cvslog] kmvc: Check palsize.

[Alex Converse]

ffmpeg | branch: master | Alex Converse <alex.converse at gmail.com> | Thu Jan 26 17:30:49 2012 +0100| [386741f887714d3e46c9e8fe577e326a7964037b] | committer: Alex Converse

kmvc: Check palsize.

Fixes: CVE-2011-3952

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Based on fix by Michael Niedermayer

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=386741f887714d3e46c9e8fe577e326a7964037b
---

 libavcodec/kmvc.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/libavcodec/kmvc.c b/libavcodec/kmvc.c
index 2b54b84..a6bb13b 100644
--- a/libavcodec/kmvc.c
+++ b/libavcodec/kmvc.c
@@ -33,6 +33,7 @@
 #define KMVC_KEYFRAME 0x80
 #define KMVC_PALETTE  0x40
 #define KMVC_METHOD   0x0F
+#define MAX_PALSIZE   256
 
 /*
  * Decoder context
@@ -43,7 +44,7 @@ typedef struct KmvcContext {
 
     int setpal;
     int palsize;
-    uint32_t pal[256];
+    uint32_t pal[MAX_PALSIZE];
     uint8_t *cur, *prev;
     uint8_t *frm0, *frm1;
     GetByteContext g;
@@ -380,6 +381,10 @@ static av_cold int decode_init(AVCodecContext * avctx)
         c->palsize = 127;
     } else {
         c->palsize = AV_RL16(avctx->extradata + 10);
+        if (c->palsize >= MAX_PALSIZE) {
+            av_log(avctx, AV_LOG_ERROR, "KMVC palette too large\n");
+            return AVERROR_INVALIDDATA;
+        }
     }
 
     if (avctx->extradata_size == 1036) {        // palette in extradata