linux-kernel - [PATCH v2] drm/msm: Fix NULL pointer dereference in crashstate_get_vm

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Message-Id: <20251112170411.479243-1-hehuiwen@kylinos.cn>
Date: Thu, 13 Nov 2025 01:04:11 +0800
From: Huiwen He <hehuiwen@...inos.cn>
To: robin.clark@....qualcomm.com
Cc: sean@...rly.run,
	konradybcio@...nel.org,
	lumag@...nel.org,
	abhinav.kumar@...ux.dev,
	jesszhan0024@...il.com,
	marijn.suijten@...ainline.org,
	airlied@...il.com,
	simona@...ll.ch,
	linux-arm-msm@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	freedreno@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Huiwen He <hehuiwen@...inos.cn>
Subject: [PATCH v2] drm/msm: Fix NULL pointer dereference in crashstate_get_vm_logs()

crashstate_get_vm_logs() did not check the return value of
kmalloc_array(). In low-memory situations, kmalloc_array() may return
NULL, leading to a NULL pointer dereference when the function later
accesses state->vm_logs.

Fix this by checking the return value of kmalloc_array() and setting
state->nr_vm_logs to 0 if allocation fails.

Fixes: 9edc52967cc7 ("drm/msm: Add VM logging for VM_BIND updates")
Signed-off-by: Huiwen He <hehuiwen@...inos.cn>
---
Changes in v2:
- Simplify the failure exit path as suggested by Rob Clark.
- Link to v1: https://lore.kernel.org/all/20251020113708.7403-1-hehuiwen@kylinos.cn

 drivers/gpu/drm/msm/msm_gpu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index 17759abc46d7..e23f70fbc8cb 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -348,6 +348,10 @@ static void crashstate_get_vm_logs(struct msm_gpu_state *state, struct msm_gem_v
 
 	state->vm_logs = kmalloc_array(
 		state->nr_vm_logs, sizeof(vm->log[0]), GFP_KERNEL);
+	if (!state->vm_logs) {
+		state->nr_vm_logs = 0;
+	}
+
 	for (int i = 0; i < state->nr_vm_logs; i++) {
 		int idx = (i + first) & vm_log_mask;
 
-- 
2.43.0