[PATCH AUTOSEL 5.13 130/219] drm/display: fix possible null-pointer dereference in dcn10_set_clock()

Sasha Levin
2021-09-09T12:24:16Z

From: Tuo Li <islituo@gmail.com>

[ Upstream commit 554594567b1fa3da74f88ec7b2dc83d000c58e98 ]

The variable dc->clk_mgr is checked in:
if (dc->clk_mgr && dc->clk_mgr->funcs->get_clock)

This indicates dc->clk_mgr can be NULL.
However, it is dereferenced in:
if (!dc->clk_mgr->funcs->get_clock)

To fix this null-pointer dereference, check dc->clk_mgr and the function
pointer dc->clk_mgr->funcs->get_clock earlier, and return if one of them
is NULL.

Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Tuo Li <islituo@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
index 7c939c0a977b..29f61a8d3e29 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
@@ -3938,13 +3938,12 @@ enum dc_status dcn10_set_clock(struct dc *dc,
struct dc_clock_config clock_cfg = {0};
struct dc_clocks *current_clocks = &context->bw_ctx.bw.dcn.clk;

- if (dc->clk_mgr && dc->clk_mgr->funcs->get_clock)
- dc->clk_mgr->funcs->get_clock(dc->clk_mgr,
- context, clock_type, &clock_cfg);
-
- if (!dc->clk_mgr->funcs->get_clock)
+ if (!dc->clk_mgr || !dc->clk_mgr->funcs->get_clock)
return DC_FAIL_UNSUPPORTED_1;

+ dc->clk_mgr->funcs->get_clock(dc->clk_mgr,
+ context, clock_type, &clock_cfg);
+
if (clk_khz > clock_cfg.max_clock_khz)
return DC_FAIL_CLK_EXCEED_MAX;

@@ -3962,7 +3961,7 @@ enum dc_status dcn10_set_clock(struct dc *dc,
else
return DC_ERROR_UNEXPECTED;

- if (dc->clk_mgr && dc->clk_mgr->funcs->update_clocks)
+ if (dc->clk_mgr->funcs->update_clocks)
dc->clk_mgr->funcs->update_clocks(dc->clk_mgr,
context, true);
return DC_OK;
--
2.30.2