[FFmpeg-cvslog] bmv: check for len being valid in bmv_decode_frame().

[Anton Khirnov]

ffmpeg | branch: release/1.1 | Anton Khirnov <anton at khirnov.net> | Thu Mar 28 10:09:36 2013 +0100| [ba31b72f462cd95609d13713fff42b1b000a56c7] | committer: Reinhard Tartler

bmv: check for len being valid in bmv_decode_frame().

It can be 0 or -1 for invalid files, which may result in invalid memory
access.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable at libav.org
(cherry picked from commit b88f902125ee808c8366e9dcb3f21e4c227483fc)

Conflicts:

	libavcodec/bmv.c

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=ba31b72f462cd95609d13713fff42b1b000a56c7
---

 libavcodec/bmv.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/bmv.c b/libavcodec/bmv.c
index a7f21ec..bcb1380 100644
--- a/libavcodec/bmv.c
+++ b/libavcodec/bmv.c
@@ -136,7 +136,7 @@ static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame,
         mode += 1 + advance_mode;
         if (mode >= 4)
             mode -= 3;
-        if (FFABS(dst_end - dst) < len)
+        if (len <= 0 || FFABS(dst_end - dst) < len)
             return -1;
         switch (mode) {
         case 1: