xxan: don't read before start of buffer in av_memcpy_backptr().

Message ID 20120314210241.2608F5E088@aruru.libav.org
State New
Headers show

Commit Message

Janne Grunau March 14, 2012, 9:02 p.m.
Module: libav
Branch: release/0.8
Commit: 8f881885c2325ce83f114437b97c2e0d6001cd7d

Author:    Ronald S. Bultje <rsbultje@gmail.com>
Committer: Reinhard Tartler <siretart@tauware.de>
Date:      Thu Mar  8 16:32:46 2012 -0800

xxan: don't read before start of buffer in av_memcpy_backptr().

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
(cherry picked from commit f1279e286b00e99f343adb51e251f036a3df6f32)

Signed-off-by: Reinhard Tartler <siretart@tauware.de>

---

 libavcodec/xxan.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

Patch

diff --git a/libavcodec/xxan.c b/libavcodec/xxan.c
index 58c80c0..12a261b 100644
--- a/libavcodec/xxan.c
+++ b/libavcodec/xxan.c
@@ -129,7 +129,8 @@  static int xan_unpack(uint8_t *dest, const int dest_len,
                 if (size + size2 > dest_end - dest)
                     break;
             }
-            if (src + size > src_end || dest + size + size2 > dest_end)
+            if (src + size > src_end || dest + size + size2 > dest_end ||
+                dest - orig_dest + size < back)
                 return -1;
             bytestream_get_buffer(&src, dest, size);
             dest += size;