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From fb82deef36a73a9518a8426e19f1b58e9de50e41 Mon Sep 17 00:00:00 2001
From: Hamza Mahfooz <hamza.mahfooz@amd.com>
Date: Tue, 27 Sep 2022 15:01:46 -0400
Subject: drm/amd/display: fix array-bounds error in
 dc_stream_remove_writeback()
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Git-commit: 5d8c3e836fc224dfe633e41f7f2856753b39a905
Patch-mainline: v6.1-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225 jsc#PED-2849

Address the following error:
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c: In function ‘dc_stream_remove_writeback’:
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:527:55: error: array subscript [0, 0] is outside array bounds of ‘struct dc_writeback_info[1]’ [-Werror=array-bounds]
  527 |                                 stream->writeback_info[j] = stream->writeback_info[i];
      |                                 ~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from ./drivers/gpu/drm/amd/amdgpu/../display/dc/dc.h:1269,
                 from ./drivers/gpu/drm/amd/amdgpu/../display/dc/inc/core_types.h:29,
                 from ./drivers/gpu/drm/amd/amdgpu/../display/dc/basics/dc_common.h:29,
                 from drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:27:
./drivers/gpu/drm/amd/amdgpu/../display/dc/dc_stream.h:241:34: note: while referencing ‘writeback_info’
  241 |         struct dc_writeback_info writeback_info[MAX_DWB_PIPES];
      |

Currently, we aren't checking to see if j remains within
writeback_info[]'s bounds. So, add a check to make sure that we aren't
overflowing the buffer.

Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/amd/display/dc/core/dc_stream.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_stream.c b/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
index 3ca1592ce7ac..ae13887756bf 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
@@ -520,7 +520,7 @@ bool dc_stream_remove_writeback(struct dc *dc,
 	}
 
 	/* remove writeback info for disabled writeback pipes from stream */
-	for (i = 0, j = 0; i < stream->num_wb_info; i++) {
+	for (i = 0, j = 0; i < stream->num_wb_info && j < MAX_DWB_PIPES; i++) {
 		if (stream->writeback_info[i].wb_enabled) {
 			if (i != j)
 				/* trim the array */
-- 
2.38.1