drm/radeon/kms/atom: fix handling of FB scratch indices

FB scratch indices are dword indices, but we were treating them as byte indices. As such, we were getting the wrong FB scratch data for non-0 indices. Fix the indices and guard the indexing against indices larger than the scratch allocation. Fixes memory corruption on some boards if data was written past the end of the FB scratch array. Signed-off-by: Alex Deucher <[email protected]> Reported-by: Dave Airlie <[email protected]> Tested-by: Dave Airlie <[email protected]> Cc: [email protected] Signed-off-by: Dave Airlie <[email protected]>
mgowda · Oct 19, 2011 · 5a6e848 · 5a6e848
1 parent a4863ca
commit 5a6e848
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Showing 2 changed files with 14 additions and 2 deletions.
diff --git 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
@@ -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;