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From:   wenyang.linux@foxmail.com
To:     Alex Deucher <alexander.deucher@amd.com>,
        Hamza Mahfooz <hamza.mahfooz@amd.com>,
        Aurabindo Pillai <aurabindo.pillai@amd.com>
Cc:     Wen Yang <wenyang.linux@foxmail.com>,
        Guenter Roeck <linux@roeck-us.net>,
        =?UTF-8?q?Harry=C2=A0Wentland=C2=A0?= <harry.wentland@amd.com>,
        =?UTF-8?q?Leo=C2=A0Li=C2=A0?= <sunpeng.li@amd.com>,
        amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH] =?UTF-8?q?drm/amd/display:=C2=A0fix=C2=A0array-bounds?= =?UTF-8?q?=C2=A0errors=C2=A0in=20dc=5Fstream=5Fremove=5Fwriteback()?=
Date:   Sun, 25 Dec 2022 23:10:58 +0800
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From: Wen Yang <wenyang.linux@foxmail.com>

The following errors occurred when using gcc 7.5.0-3ubuntu1~18.04:
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:543:55: warning: array subscript is above array bounds [-Warray-bounds]
     stream->writeback_info[j] = stream->writeback_info[i];
                                 ~~~~~~~~~~~~~~~~~~~~~~^~~
Add a check to make sure that num_wb_info won't overflowing the writeback_info buffer.

Fixes: 6fbefb84a98e ("drm/amd/display: Add DC core changes for DCN2")

Signed-off-by: Wen Yang <wenyang.linux@foxmail.com>
Cc: Aurabindo Pillai <aurabindo.pillai@amd.com>
Cc: Hamza Mahfooz <hamza.mahfooz@amd.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Leo Li <sunpeng.li@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/gpu/drm/amd/display/dc/core/dc_stream.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 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 20e534f73513..9825c30f2ca0 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
@@ -481,6 +481,7 @@ bool dc_stream_add_writeback(struct dc *dc,
 	}
 
 	if (!isDrc) {
+		ASSERT(stream->num_wb_info + 1 <= MAX_DWB_PIPES);
 		stream->writeback_info[stream->num_wb_info++] = *wb_info;
 	}
 
@@ -526,6 +527,11 @@ bool dc_stream_remove_writeback(struct dc *dc,
 		return false;
 	}
 
+	if (stream->num_wb_info > MAX_DWB_PIPES) {
+		dm_error("DC: num_wb_info is invalid!\n");
+		return false;
+	}
+
 //	stream->writeback_info[dwb_pipe_inst].wb_enabled = false;
 	for (i = 0; i < stream->num_wb_info; i++) {
 		/*dynamic update*/
@@ -540,7 +546,8 @@ bool dc_stream_remove_writeback(struct dc *dc,
 		if (stream->writeback_info[i].wb_enabled) {
 			if (j < i)
 				/* trim the array */
-				stream->writeback_info[j] = stream->writeback_info[i];
+				memcpy(&stream->writeback_info[j], &stream->writeback_info[i],
+						sizeof(struct dc_writeback_info));
 			j++;
 		}
 	}
-- 
2.25.1