[PATCH AUTOSEL 6.10 27/34] drm/amd/display: Fix NULL pointer dereference for DTN log in DCN401

Sasha Levin
2024-07-28T15:44:55Z

From: Rodrigo Siqueira <rodrigo.siqueira@amd.com>

[ Upstream commit 5af757124792817f8eb1bd0c80ad60fab519586b ]

When users run the command:

cat /sys/kernel/debug/dri/0/amdgpu_dm_dtn_log

The following NULL pointer dereference happens:

[ +0.000003] BUG: kernel NULL pointer dereference, address: NULL
[ +0.000005] #PF: supervisor instruction fetch in kernel mode
[ +0.000002] #PF: error_code(0x0010) - not-present page
[ +0.000002] PGD 0 P4D 0
[ +0.000004] Oops: 0010 [#1] PREEMPT SMP NOPTI
[ +0.000003] RIP: 0010:0x0
[ +0.000008] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
[...]
[ +0.000002] PKRU: 55555554
[ +0.000002] Call Trace:
[ +0.000002] <TASK>
[ +0.000003] ? show_regs+0x65/0x70
[ +0.000006] ? __die+0x24/0x70
[ +0.000004] ? page_fault_oops+0x160/0x470
[ +0.000006] ? do_user_addr_fault+0x2b5/0x690
[ +0.000003] ? prb_read_valid+0x1c/0x30
[ +0.000005] ? exc_page_fault+0x8c/0x1a0
[ +0.000005] ? asm_exc_page_fault+0x27/0x30
[ +0.000012] dcn10_log_color_state+0xf9/0x510 [amdgpu]
[ +0.000306] ? srso_alias_return_thunk+0x5/0xfbef5
[ +0.000003] ? vsnprintf+0x2fb/0x600
[ +0.000009] dcn10_log_hw_state+0xfd0/0xfe0 [amdgpu]
[ +0.000218] ? __mod_memcg_lruvec_state+0xe8/0x170
[ +0.000008] ? srso_alias_return_thunk+0x5/0xfbef5
[ +0.000002] ? debug_smp_processor_id+0x17/0x20
[ +0.000003] ? srso_alias_return_thunk+0x5/0xfbef5
[ +0.000002] ? srso_alias_return_thunk+0x5/0xfbef5
[ +0.000002] ? set_ptes.isra.0+0x2b/0x90
[ +0.000004] ? srso_alias_return_thunk+0x5/0xfbef5
[ +0.000002] ? _raw_spin_unlock+0x19/0x40
[ +0.000004] ? srso_alias_return_thunk+0x5/0xfbef5
[ +0.000002] ? do_anonymous_page+0x337/0x700
[ +0.000004] dtn_log_read+0x82/0x120 [amdgpu]
[ +0.000207] full_proxy_read+0x66/0x90
[ +0.000007] vfs_read+0xb0/0x340
[ +0.000005] ? __count_memcg_events+0x79/0xe0
[ +0.000002] ? srso_alias_return_thunk+0x5/0xfbef5
[ +0.000003] ? count_memcg_events.constprop.0+0x1e/0x40
[ +0.000003] ? handle_mm_fault+0xb2/0x370
[ +0.000003] ksys_read+0x6b/0xf0
[ +0.000004] __x64_sys_read+0x19/0x20
[ +0.000003] do_syscall_64+0x60/0x130
[ +0.000004] entry_SYSCALL_64_after_hwframe+0x6e/0x76
[ +0.000003] RIP: 0033:0x7fdf32f147e2
[...]

This error happens when the color log tries to read the gamut remap
information from DCN401 which is not initialized in the dcn401_dpp_funcs
which leads to a null pointer dereference. This commit addresses this
issue by adding a proper guard to access the gamut_remap callback in
case the specific ASIC did not implement this function.

Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../amd/display/dc/hwss/dcn10/dcn10_hwseq.c | 49 ++++++++++---------
1 file changed, 27 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn10/dcn10_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn10/dcn10_hwseq.c
index 0c4aef8ffe2c5..3306684e805ac 100644
--- a/drivers/gpu/drm/amd/display/dc/hwss/dcn10/dcn10_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn10/dcn10_hwseq.c
@@ -288,6 +288,7 @@ static void dcn10_log_color_state(struct dc *dc,
{
struct dc_context *dc_ctx = dc->ctx;
struct resource_pool *pool = dc->res_pool;
+ bool is_gamut_remap_available = false;
int i;

DTN_INFO("DPP: IGAM format IGAM mode DGAM mode RGAM mode"
@@ -300,16 +301,15 @@ static void dcn10_log_color_state(struct dc *dc,
struct dcn_dpp_state s = {0};

dpp->funcs->dpp_read_state(dpp, &s);
- dpp->funcs->dpp_get_gamut_remap(dpp, &s.gamut_remap);
+ if (dpp->funcs->dpp_get_gamut_remap) {
+ dpp->funcs->dpp_get_gamut_remap(dpp, &s.gamut_remap);
+ is_gamut_remap_available = true;
+ }

if (!s.is_enabled)
continue;

- DTN_INFO("[%2d]: %11xh %11s %9s %9s"
- " %12s "
- "%010lld %010lld %010lld %010lld "
- "%010lld %010lld %010lld %010lld "
- "%010lld %010lld %010lld %010lld",
+ DTN_INFO("[%2d]: %11xh %11s %9s %9s",
dpp->inst,
s.igam_input_format,
(s.igam_lut_mode == 0) ? "BypassFixed" :
@@ -328,22 +328,27 @@ static void dcn10_log_color_state(struct dc *dc,
((s.rgam_lut_mode == 2) ? "Ycc" :
((s.rgam_lut_mode == 3) ? "RAM" :
((s.rgam_lut_mode == 4) ? "RAM" :
- "Unknown")))),
- (s.gamut_remap.gamut_adjust_type == 0) ? "Bypass" :
- ((s.gamut_remap.gamut_adjust_type == 1) ? "HW" :
- "SW"),
- s.gamut_remap.temperature_matrix[0].value,
- s.gamut_remap.temperature_matrix[1].value,
- s.gamut_remap.temperature_matrix[2].value,
- s.gamut_remap.temperature_matrix[3].value,
- s.gamut_remap.temperature_matrix[4].value,
- s.gamut_remap.temperature_matrix[5].value,
- s.gamut_remap.temperature_matrix[6].value,
- s.gamut_remap.temperature_matrix[7].value,
- s.gamut_remap.temperature_matrix[8].value,
- s.gamut_remap.temperature_matrix[9].value,
- s.gamut_remap.temperature_matrix[10].value,
- s.gamut_remap.temperature_matrix[11].value);
+ "Unknown")))));
+ if (is_gamut_remap_available)
+ DTN_INFO(" %12s "
+ "%010lld %010lld %010lld %010lld "
+ "%010lld %010lld %010lld %010lld "
+ "%010lld %010lld %010lld %010lld",
+ (s.gamut_remap.gamut_adjust_type == 0) ? "Bypass" :
+ ((s.gamut_remap.gamut_adjust_type == 1) ? "HW" : "SW"),
+ s.gamut_remap.temperature_matrix[0].value,
+ s.gamut_remap.temperature_matrix[1].value,
+ s.gamut_remap.temperature_matrix[2].value,
+ s.gamut_remap.temperature_matrix[3].value,
+ s.gamut_remap.temperature_matrix[4].value,
+ s.gamut_remap.temperature_matrix[5].value,
+ s.gamut_remap.temperature_matrix[6].value,
+ s.gamut_remap.temperature_matrix[7].value,
+ s.gamut_remap.temperature_matrix[8].value,
+ s.gamut_remap.temperature_matrix[9].value,
+ s.gamut_remap.temperature_matrix[10].value,
+ s.gamut_remap.temperature_matrix[11].value);
+
DTN_INFO("\n");
}
DTN_INFO("\n");
--
2.43.0