linux-kernel - [PATCH v2] drm: Account property blob allocations to memcg

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Message-ID: <tencent_817B74448A3DED2A1535F6290308666E4206@qq.com>
Date: Mon,  5 Jan 2026 11:14:13 -0500
From: Xiao Kan <814091656@...com>
To: maarten.lankhorst@...ux.intel.com,
	mripard@...nel.org,
	tzimmermann@...e.de,
	airlied@...il.com,
	simona@...ll.ch,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Cc: w@....eu,
	security@...nel.org,
	kanxiao666@...il.com,
	xiao.kan@...sung.com,
	Xiao Kan <814091656@...com>
Subject: [PATCH v2] drm: Account property blob allocations to memcg

DRM_IOCTL_MODE_CREATEPROPBLOB allows userspace to allocate arbitrary-sized
property blobs backed by kernel memory.

Currently, the blob data allocation is not accounted to the allocating
process's memory cgroup, allowing unprivileged users to trigger unbounded
kernel memory consumption and potentially cause system-wide OOM.

Mark the property blob data allocation with GFP_ACCOUNT so that the memory
is properly charged to the caller's memcg. This ensures existing cgroup
memory limits apply and prevents uncontrolled kernel memory growth without
introducing additional policy or per-file limits.

Changes since v1:
  - Drop the per-drm_file blob count limit.
  - Account blob data allocations to memcg via GFP_KERNEL_ACCOUNT instead.

Signed-off-by: Xiao Kan <814091656@...com>
Signed-off-by: Xiao Kan <xiao.kan@...sung.com>
---
 drivers/gpu/drm/drm_property.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_property.c b/drivers/gpu/drm/drm_property.c
index 596272149..a34758712 100755
--- a/drivers/gpu/drm/drm_property.c
+++ b/drivers/gpu/drm/drm_property.c
@@ -562,7 +562,7 @@ drm_property_create_blob(struct drm_device *dev, size_t length,
 	if (!length || length > INT_MAX - sizeof(struct drm_property_blob))
 		return ERR_PTR(-EINVAL);
 
-	blob = kvzalloc(sizeof(struct drm_property_blob)+length, GFP_KERNEL);
+	blob = kvzalloc(sizeof(struct drm_property_blob)+length, GFP_KERNEL_ACCOUNT);
 	if (!blob)
 		return ERR_PTR(-ENOMEM);
 
-- 
2.51.0