linux-kernel - [PATCH AUTOSEL 6.6 23/83] drm/amdkfd: Check debug trap enable before write dbg_ev

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Message-ID: <20240801002107.3934037-23-sashal@kernel.org>
Date: Wed, 31 Jul 2024 20:17:38 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: "Lin.Cao" <lincao12@....com>,
	Jonathan Kim <jonathan.kim@....com>,
	Alex Deucher <alexander.deucher@....com>,
	Sasha Levin <sashal@...nel.org>,
	Felix.Kuehling@....com,
	christian.koenig@....com,
	Xinhui.Pan@....com,
	airlied@...il.com,
	daniel@...ll.ch,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.6 23/83] drm/amdkfd: Check debug trap enable before write dbg_ev_file

From: "Lin.Cao" <lincao12@....com>

[ Upstream commit 547033b593063eb85bfdf9b25a5f1b8fd1911be2 ]

In interrupt context, write dbg_ev_file will be run by work queue. It
will cause write dbg_ev_file execution after debug_trap_disable, which
will cause NULL pointer access.
v2: cancel work "debug_event_workarea" before set dbg_ev_file as NULL.

Signed-off-by: Lin.Cao <lincao12@....com>
Reviewed-by: Jonathan Kim <jonathan.kim@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/amdkfd/kfd_debug.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_debug.c b/drivers/gpu/drm/amd/amdkfd/kfd_debug.c
index 9ec750666382f..94aaf2fc556ca 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_debug.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_debug.c
@@ -103,7 +103,8 @@ void debug_event_write_work_handler(struct work_struct *work)
 			struct kfd_process,
 			debug_event_workarea);
 
-	kernel_write(process->dbg_ev_file, &write_data, 1, &pos);
+	if (process->debug_trap_enabled && process->dbg_ev_file)
+		kernel_write(process->dbg_ev_file, &write_data, 1, &pos);
 }
 
 /* update process/device/queue exception status, write to descriptor
@@ -645,6 +646,7 @@ int kfd_dbg_trap_disable(struct kfd_process *target)
 	else if (target->runtime_info.runtime_state != DEBUG_RUNTIME_STATE_DISABLED)
 		target->runtime_info.runtime_state = DEBUG_RUNTIME_STATE_ENABLED;
 
+	cancel_work_sync(&target->debug_event_workarea);
 	fput(target->dbg_ev_file);
 	target->dbg_ev_file = NULL;
 
-- 
2.43.0