1 files changed, 14 insertions, 3 deletions

diff --git a/linden/indra/newview/llvlcomposition.cpp b/linden/indra/newview/llvlcomposition.cpp
index f2fa1e6..e0cb40d 100644
--- a/linden/indra/newview/llvlcomposition.cpp
+++ b/linden/indra/newview/llvlcomposition.cpp
@@ -269,6 +269,7 @@ BOOL LLVLComposition::generateTexture(const F32 x, const F32 y,
 
         // These have already been validated by generateComposition.
         U8* st_data[4];
+        S32 st_data_size[4]; // for debugging
 
         for (S32 i = 0; i < 4; i++)
         {
@@ -299,6 +300,7 @@ BOOL LLVLComposition::generateTexture(const F32 x, const F32 y,
                         }
                 }
                 st_data[i] = mRawImages[i]->getData();
+                st_data_size[i] = mRawImages[i]->getDataSize();
         }
 
         ///////////////////////////////////////
@@ -413,9 +415,18 @@ BOOL LLVLComposition::generateTexture(const F32 x, const F32 y,
                         for (U32 k = 0; k < tex_comps; k++)
                         {
                                 // Linearly interpolate based on composition.
-                                F32 a = *(st_data[tex0] + st_offset);
-                                F32 b = *(st_data[tex1] + st_offset);
-                                rawp[ offset ] = (U8)lltrunc( a + composition * (b - a) );
+                                if (st_offset >= st_data_size[tex0] || st_offset >= st_data_size[tex1])
+                                {
+                                        // SJB: This shouldn't be happening, but does... Rounding error?
+                                        //llwarns << "offset 0 [" << tex0 << "] =" << st_offset << " >= size=" << st_data_size[tex0] << llendl;
+                                        //llwarns << "offset 1 [" << tex1 << "] =" << st_offset << " >= size=" << st_data_size[tex1] << llendl;
+                                }
+                                else
+                                {
+                                        F32 a = *(st_data[tex0] + st_offset);
+                                        F32 b = *(st_data[tex1] + st_offset);
+                                        rawp[ offset ] = (U8)lltrunc( a + composition * (b - a) );
+                                }
                                 offset++;
                                 st_offset++;
                         }