2 files changed, 14 insertions, 2 deletions

diff --git a/drivers/gpu/drm/radeon/atom.c b/drivers/gpu/drm/radeon/atom.c
index e88c64417a8a..14cc88aaf3a7 100644
--- a/drivers/gpu/drm/radeon/atom.c
+++ b/drivers/gpu/drm/radeon/atom.c
@@ -277,7 +277,12 @@ static uint32_t atom_get_src_int(atom_exec_context *ctx, uint8_t attr,
         case ATOM_ARG_FB:
                 idx = U8(*ptr);
                 (*ptr)++;
-                val = gctx->scratch[((gctx->fb_base + idx) / 4)];
+                if ((gctx->fb_base + (idx * 4)) > gctx->scratch_size_bytes) {
+                        DRM_ERROR("ATOM: fb read beyond scratch region: %d vs. %d\n",
+                                  gctx->fb_base + (idx * 4), gctx->scratch_size_bytes);
+                        val = 0;
+                } else
+                        val = gctx->scratch[(gctx->fb_base / 4) + idx];
                 if (print)
                         DEBUG("FB[0x%02X]", idx);
                 break;
@@ -531,7 +536,11 @@ static void atom_put_dst(atom_exec_context *ctx, int arg, uint8_t attr,
         case ATOM_ARG_FB:
                 idx = U8(*ptr);
                 (*ptr)++;
-                gctx->scratch[((gctx->fb_base + idx) / 4)] = val;
+                if ((gctx->fb_base + (idx * 4)) > gctx->scratch_size_bytes) {
+                        DRM_ERROR("ATOM: fb write beyond scratch region: %d vs. %d\n",
+                                  gctx->fb_base + (idx * 4), gctx->scratch_size_bytes);
+                } else
+                        gctx->scratch[(gctx->fb_base / 4) + idx] = val;
                 DEBUG("FB[0x%02X]", idx);
                 break;
         case ATOM_ARG_PLL:
@@ -1370,11 +1379,13 @@ int atom_allocate_fb_scratch(struct atom_context *ctx)
 
                 usage_bytes = firmware_usage->asFirmwareVramReserveInfo[0].usFirmwareUseInKb * 1024;
         }
+        ctx->scratch_size_bytes = 0;
         if (usage_bytes == 0)
                 usage_bytes = 20 * 1024;
         /* allocate some scratch memory */
         ctx->scratch = kzalloc(usage_bytes, GFP_KERNEL);
         if (!ctx->scratch)
                 return -ENOMEM;
+        ctx->scratch_size_bytes = usage_bytes;
         return 0;
 }
diff --git a/drivers/gpu/drm/radeon/atom.h b/drivers/gpu/drm/radeon/atom.h
index a589a55b223e..93cfe2086ba0 100644
--- a/drivers/gpu/drm/radeon/atom.h
+++ b/drivers/gpu/drm/radeon/atom.h
@@ -137,6 +137,7 @@ struct atom_context {
         int cs_equal, cs_above;
         int io_mode;
         uint32_t *scratch;
+        int scratch_size_bytes;
 };
 
 extern int atom_debug;