CVE-2013-7009 (published 2013-12-09T16:36Z)

The rpza_decode_stream function in libavcodec/rpza.c in FFmpeg before 2.1 does not properly maintain a pointer to pixel data, which allows remote attackers to cause a denial of service (out-of-bounds array access) or possibly have unspecified other impact via crafted Apple RPZA data.

Severity: MEDIUM
CVSS v2 base score: 6.8 (AV:N/AC:M/Au:N/C:P/I:P/A:P)

Weakness information:
cwe_id: CWE-119
cwe_name: Improper Restriction of Operations within the Bounds of a Memory Buffer
description: The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
extended_description: 
            Certain languages allow direct addressing of memory locations and do not automatically ensure that these locations are valid for the memory buffer that is being referenced. This can cause read or write operations to be performed on memory locations that may be associated with other variables, data structures, or internal program data.
         
         

Fix information:
repo_url: https://github.com/FFmpeg/FFmpeg
commit_details: repo_url: https://github.com/FFmpeg/FFmpeg
author: Michael Niedermayer
author_date: 2013-08-22 01:07:32+02:00
msg: avcodec/rpza: Perform pointer advance and checks before using the pointers

Fixes out of array accesses
Fixes Ticket2850

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
repository: repo_url: https://github.com/FFmpeg/FFmpeg
repo_name: FFmpeg/FFmpeg
description: Mirror of https://git.ffmpeg.org/ffmpeg.git
repo_language: C
owner: FFmpeg
file_changes: filename: rpza.c
change_type: ModificationType.MODIFY
diff: @@ -85,7 +85,7 @@ static void rpza_decode_stream(RpzaContext *s)
     unsigned short *pixels = (unsigned short *)s->frame.data[0];
 
     int row_ptr = 0;
-    int pixel_ptr = 0;
+    int pixel_ptr = -4;
     int block_ptr;
     int pixel_x, pixel_y;
     int total_blocks;
@@ -141,6 +141,7 @@ static void rpza_decode_stream(RpzaContext *s)
             colorA = AV_RB16 (&s->buf[stream_ptr]);
             stream_ptr += 2;
             while (n_blocks--) {
+                ADVANCE_BLOCK()
                 block_ptr = row_ptr + pixel_ptr;
                 for (pixel_y = 0; pixel_y < 4; pixel_y++) {
                     for (pixel_x = 0; pixel_x < 4; pixel_x++){
@@ -149,7 +150,6 @@ static void rpza_decode_stream(RpzaContext *s)
                     }
                     block_ptr += row_inc;
                 }
-                ADVANCE_BLOCK();
             }
             break;
 
@@ -188,6 +188,7 @@ static void rpza_decode_stream(RpzaContext *s)
             if (s->size - stream_ptr < n_blocks * 4)
                 return;
             while (n_blocks--) {
+                ADVANCE_BLOCK();
                 block_ptr = row_ptr + pixel_ptr;
                 for (pixel_y = 0; pixel_y < 4; pixel_y++) {
                     index = s->buf[stream_ptr++];
@@ -198,7 +199,6 @@ static void rpza_decode_stream(RpzaContext *s)
                     }
                     block_ptr += row_inc;
                 }
-                ADVANCE_BLOCK();
             }
             break;
 
@@ -206,6 +206,7 @@ static void rpza_decode_stream(RpzaContext *s)
         case 0x00:
             if (s->size - stream_ptr < 16)
                 return;
+            ADVANCE_BLOCK();
             block_ptr = row_ptr + pixel_ptr;
             for (pixel_y = 0; pixel_y < 4; pixel_y++) {
                 for (pixel_x = 0; pixel_x < 4; pixel_x++){
@@ -219,7 +220,6 @@ static void rpza_decode_stream(RpzaContext *s)
                 }
                 block_ptr += row_inc;
             }
-            ADVANCE_BLOCK();
             break;
 
         /* Unknown opcode */

programming_language: C