shithub: libvpx

Info  •  Files  •  Log  •  Branches

Added clamp of qindex to valid range

The qindex for a segment was not clamped in ABSDATA mode, which may
cause invalid memory access if an ill-formed stream has a negative
value in ABSDATA mode. This commit added clamp to make sure qindex
for a segment always fall into valid range.

Change-Id: I0a74d00f4ef40aec7edaeca1d03c8645e23ab08c

--- a/vp9/common/vp9_quant_common.c

+++ b/vp9/common/vp9_quant_common.c

@@ -134,9 +134,9 @@

                    int base_qindex) {

   if (vp9_segfeature_active(seg, segment_id, SEG_LVL_ALT_Q)) {

     const int data = vp9_get_segdata(seg, segment_id, SEG_LVL_ALT_Q);

-    return seg->abs_delta == SEGMENT_ABSDATA ?

-                             data :  // Abs value

-                             clamp(base_qindex + data, 0, MAXQ);  // Delta value

+    const int seg_qindex = seg->abs_delta == SEGMENT_ABSDATA ?

+        data : base_qindex + data;

+    return clamp(seg_qindex, 0, MAXQ);

   } else {

     return base_qindex;

   }

-- 

⑨