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

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Message-ID: <20251020113708.7403-1-hehuiwen@kylinos.cn>
Date: Mon, 20 Oct 2025 19:37:08 +0800
From: Huiwen He <hehuiwen@...inos.cn>
To: Rob Clark <robin.clark@....qualcomm.com>
Cc: Dmitry Baryshkov <lumag@...nel.org>,
	David Airlie <airlied@...il.com>,
	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] drm/msm: Fix NULL pointer dereference in crashstate_get_vm_logs()

crashstate_get_vm_logs() did not check the result of kmalloc_array()
before using state->vm_logs. In low memory situations, kmalloc_array()
may fail and return NULL, leading to a kernel crash when the array
is accessed in the subsequent loop.

Fix this by checking the return value of kmalloc_array(). If allocation
fails, set state->nr_vm_logs to 0, and exit the function safely.

Fixes: 9edc52967cc7 ("drm/msm: Add VM logging for VM_BIND updates")
Signed-off-by: Huiwen He <hehuiwen@...inos.cn>
---
 drivers/gpu/drm/msm/msm_gpu.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index 17759abc46d7..51df6ff945d2 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -348,6 +348,12 @@ 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;
+		mutex_unlock(&vm->mmu_lock);
+		return;
+	}
+
 	for (int i = 0; i < state->nr_vm_logs; i++) {
 		int idx = (i + first) & vm_log_mask;
 
-- 
2.43.0