linux-kernel - [PATCH AUTOSEL 6.11 139/244] drm/amd/display: Add NULL check for clk_mgr and clk_mgr->funcs in dcn401_init

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Message-ID: <20240925113641.1297102-139-sashal@kernel.org>
Date: Wed, 25 Sep 2024 07:26:00 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Srinivasan Shanmugam <srinivasan.shanmugam@....com>,
	Tom Chung <chiahsuan.chung@....com>,
	Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
	Roman Li <roman.li@....com>,
	Alex Hung <alex.hung@....com>,
	Aurabindo Pillai <aurabindo.pillai@....com>,
	Harry Wentland <harry.wentland@....com>,
	Hamza Mahfooz <hamza.mahfooz@....com>,
	Alex Deucher <alexander.deucher@....com>,
	Sasha Levin <sashal@...nel.org>,
	sunpeng.li@....com,
	christian.koenig@....com,
	Xinhui.Pan@....com,
	airlied@...il.com,
	daniel@...ll.ch,
	sarvinde@....com,
	alvin.lee2@....com,
	nevenko.stupar@....com,
	wenjing.liu@....com,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.11 139/244] drm/amd/display: Add NULL check for clk_mgr and clk_mgr->funcs in dcn401_init_hw

From: Srinivasan Shanmugam <srinivasan.shanmugam@....com>

[ Upstream commit 4b6377f0e96085cbec96eb7f0b282430ccdd3d75 ]

This commit addresses a potential null pointer dereference issue in the
`dcn401_init_hw` function. The issue could occur when `dc->clk_mgr` or
`dc->clk_mgr->funcs` is null.

The fix adds a check to ensure `dc->clk_mgr` and `dc->clk_mgr->funcs` is
not null before accessing its functions. This prevents a potential null
pointer dereference.

Reported by smatch:
drivers/gpu/drm/amd/amdgpu/../display/dc/hwss/dcn401/dcn401_hwseq.c:416 dcn401_init_hw() error: we previously assumed 'dc->clk_mgr' could be null (see line 225)

Cc: Tom Chung <chiahsuan.chung@....com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@....com>
Cc: Roman Li <roman.li@....com>
Cc: Alex Hung <alex.hung@....com>
Cc: Aurabindo Pillai <aurabindo.pillai@....com>
Cc: Harry Wentland <harry.wentland@....com>
Cc: Hamza Mahfooz <hamza.mahfooz@....com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@....com>
Reviewed-by: Alex Hung <alex.hung@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c
index 2c50c0f745a0b..324e77ceaf1cf 100644
--- a/drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c
@@ -222,7 +222,7 @@ void dcn401_init_hw(struct dc *dc)
 	uint32_t backlight = MAX_BACKLIGHT_LEVEL;
 	uint32_t user_level = MAX_BACKLIGHT_LEVEL;
 
-	if (dc->clk_mgr && dc->clk_mgr->funcs->init_clocks) {
+	if (dc->clk_mgr && dc->clk_mgr->funcs && dc->clk_mgr->funcs->init_clocks) {
 		dc->clk_mgr->funcs->init_clocks(dc->clk_mgr);
 
 		// mark dcmode limits present if any clock has distinct AC and DC values from SMU
@@ -413,7 +413,7 @@ void dcn401_init_hw(struct dc *dc)
 	if (!dcb->funcs->is_accelerated_mode(dcb) && dc->res_pool->hubbub->funcs->init_watermarks)
 		dc->res_pool->hubbub->funcs->init_watermarks(dc->res_pool->hubbub);
 
-	if (dc->clk_mgr->funcs->notify_wm_ranges)
+	if (dc->clk_mgr && dc->clk_mgr->funcs && dc->clk_mgr->funcs->notify_wm_ranges)
 		dc->clk_mgr->funcs->notify_wm_ranges(dc->clk_mgr);
 
 	if (dc->clk_mgr->funcs->set_hard_max_memclk && !dc->clk_mgr->dc_mode_softmax_enabled)
@@ -438,7 +438,9 @@ void dcn401_init_hw(struct dc *dc)
 		dc->debug.fams2_config.bits.enable &= dc->ctx->dmub_srv->dmub->feature_caps.fw_assisted_mclk_switch_ver == 2;
 		if (!dc->debug.fams2_config.bits.enable && dc->res_pool->funcs->update_bw_bounding_box) {
 			/* update bounding box if FAMS2 disabled */
-			dc->res_pool->funcs->update_bw_bounding_box(dc, dc->clk_mgr->bw_params);
+			if (dc->clk_mgr)
+				dc->res_pool->funcs->update_bw_bounding_box(dc,
+									    dc->clk_mgr->bw_params);
 		}
 	}
 }
-- 
2.43.0