linux-kernel - [PATCH AUTOSEL 5.15 41/69] drm/amdgpu/display/dc: Fix null pointer exception

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Date:   Thu, 11 Aug 2022 11:55:50 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Rahul Kumar <rahul.kumar1@....com>,
        Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
        Harry Wentland <harry.wentland@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>, sunpeng.li@....com,
        christian.koenig@....com, Xinhui.Pan@....com, airlied@...ux.ie,
        daniel@...ll.ch, Anthony.Koo@....com, Aric.Cyr@....com,
        alex.hung@....com, Yi-Ling.Chen2@....com, Roman.Li@....com,
        hanghong.ma@....com, mwen@...lia.com, dillon.varone@....com,
        Jerry.Zuo@....com, agustin.gutierrez@....com, dale.zhao@....com,
        isabbasso@...eup.net, Sungjoon.Kim@....com,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 5.15 41/69] drm/amdgpu/display/dc: Fix null pointer exception

From: Rahul Kumar <rahul.kumar1@....com>

[ Upstream commit 1c4dae3e4639540fb567e570cc56a3c292afb6fe ]

We observed hard hang due to NULL derefrence This issue is seen after
running system all the time after two or three days

struct dc *dc = plane_state->ctx->dc; Randomly in long run we found
plane_state or plane_state->ctx is found NULL which causes exception.

BUG: kernel NULL pointer dereference, address: 0000000000000000
PF: supervisor read access in kernel mode
PF: error_code(0x0000) - not-present page
PGD 1dc7f2067 P4D 1dc7f2067 PUD 222c75067 PMD 0
Oops: 0000 [#1] SMP NOPTI
CPU: 5 PID: 29855 Comm: kworker/u16:4 ...
...
Workqueue: events_unbound commit_work [drm_kms_helper]
RIP: 0010:dcn10_update_pending_status+0x1f/0xee [amdgpu]
Code: 41 5f c3 0f 1f 44 00 00 b0 01 c3 0f 1f 44 00 00 41 55 41 54 55 53 48 8b 1f 4c 8b af f8 00 00 00 48 8b 83 88 03 00 00 48 85 db <4c> 8b 20 0f 84 bf 00 00 00 48 89 fd 48 8b bf b8 00 00 00 48 8b 07
RSP: 0018:ffff942941997ab8 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff8d7fd98d2000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff8d7e3e87c708 RDI: ffff8d7f2d8c0690
RBP: ffff8d7f2d8c0000 R08: ffff942941997a34 R09: 00000000ffffffff
R10: 0000000000005000 R11: 00000000000000f0 R12: ffff8d7f2d8c0690
R13: ffff8d8035a41680 R14: 00000000000186a0 R15: ffff8d7f2d8c1dd8
FS:  0000000000000000(0000) GS:ffff8d8037340000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000148030000 CR4: 00000000003406e0
Call Trace:
 dc_commit_state+0x6a2/0x7f0 [amdgpu]
 amdgpu_dm_atomic_commit_tail+0x460/0x19bb [amdgpu]

Tested-by: Rodrigo Siqueira <Rodrigo.Siqueira@....com>
Reviewed-by: Harry Wentland <harry.wentland@....com>
Signed-off-by: Rahul Kumar <rahul.kumar1@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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 93f31e4aeecb..c55eb137bd81 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
@@ -3142,7 +3142,7 @@ void dcn10_update_pending_status(struct pipe_ctx *pipe_ctx)
 	struct dc_plane_state *plane_state = pipe_ctx->plane_state;
 	struct timing_generator *tg = pipe_ctx->stream_res.tg;
 	bool flip_pending;
-	struct dc *dc = plane_state->ctx->dc;
+	struct dc *dc = pipe_ctx->stream->ctx->dc;
 
 	if (plane_state == NULL)
 		return;
-- 
2.35.1