CVE-2013-7011 (published 2013-12-09T16:36Z)

The read_header function in libavcodec/ffv1dec.c in FFmpeg before 2.1 does not prevent changes to global parameters, which allows remote attackers to cause a denial of service (out-of-bounds array access) or possibly have unspecified other impact via crafted FFV1 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: 2013-08-30 04:51:09+02:00
msg: ffv1dec: check that global parameters dont change in version 0/1

Such changes are not allowed nor supported

Fixes Ticket2906

Found-by: ami_stuff
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: ffv1dec.c
change_type: ModificationType.MODIFY
diff: @@ -580,6 +580,7 @@ static int read_header(FFV1Context *f)
     memset(state, 128, sizeof(state));
 
     if (f->version < 2) {
+        int chroma_planes, chroma_h_shift, chroma_v_shift, transparency;
         unsigned v= get_symbol(c, state, 0);
         if (v >= 2) {
             av_log(f->avctx, AV_LOG_ERROR, "invalid version %d in ver01 header\n", v);
@@ -597,10 +598,26 @@ static int read_header(FFV1Context *f)
         if (f->version > 0)
             f->avctx->bits_per_raw_sample = get_symbol(c, state, 0);
 
-        f->chroma_planes  = get_rac(c, state);
-        f->chroma_h_shift = get_symbol(c, state, 0);
-        f->chroma_v_shift = get_symbol(c, state, 0);
-        f->transparency   = get_rac(c, state);
+        chroma_planes  = get_rac(c, state);
+        chroma_h_shift = get_symbol(c, state, 0);
+        chroma_v_shift = get_symbol(c, state, 0);
+        transparency   = get_rac(c, state);
+
+        if (f->plane_count) {
+            if (   chroma_planes != f->chroma_planes
+                || chroma_h_shift!= f->chroma_h_shift
+                || chroma_v_shift!= f->chroma_v_shift
+                || transparency  != f->transparency) {
+                av_log(f->avctx, AV_LOG_ERROR, "Invalid change of global parameters\n");
+                return AVERROR_INVALIDDATA;
+            }
+        }
+
+        f->chroma_planes  = chroma_planes;
+        f->chroma_h_shift = chroma_h_shift;
+        f->chroma_v_shift = chroma_v_shift;
+        f->transparency   = transparency;
+
         f->plane_count    = 2 + f->transparency;
     }
 

programming_language: C