linux-kernel - [PATCH v2] media: videobuf2: forbid remove

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Message-Id: <20251020160121.1985354-1-m.szyprowski@samsung.com>
Date: Mon, 20 Oct 2025 18:01:21 +0200
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Marek Szyprowski <m.szyprowski@...sung.com>, Tomasz Figa
	<tfiga@...omium.org>, Mauro Carvalho Chehab <mchehab@...nel.org>, Guennadi
	Liakhovetski <g.liakhovetski@....de>, Benjamin Gaignard
	<benjamin.gaignard@...labora.com>, Hans Verkuil <hverkuil@...nel.org>,
	stable@...r.kernel.org, Shuangpeng Bai <SJB7183@....edu>
Subject: [PATCH v2] media: videobuf2: forbid remove_bufs when legacy fileio
 is active

vb2_ioctl_remove_bufs() call manipulates queue internal buffer list,
potentially overwriting some pointers used by the legacy fileio access
mode. Add a vb2_verify_memory_type() check symmetrical to
vb2_ioctl_create_bufs() to forbid that ioctl when fileio is active to
protect internal queue state between subsequent read/write calls.

CC: stable@...r.kernel.org
Fixes: a3293a85381e ("media: v4l2: Add REMOVE_BUFS ioctl")
Reported-by: Shuangpeng Bai<SJB7183@....edu>
Suggested-by: Benjamin Gaignard <benjamin.gaignard@...labora.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
---
v2:
- dropped a change to vb2_ioctl_create_bufs(), as it is already handled
  by the vb2_verify_memory_type() call
- replaced queue->type check in vb2_ioctl_remove_bufs() by a call to
  vb2_verify_memory_type() which covers all cases

v1: https://lore.kernel.org/all/20251016111154.993949-1-m.szyprowski@samsung.com/
---
 drivers/media/common/videobuf2/videobuf2-v4l2.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index d911021c1bb0..0de7490292fe 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -1000,9 +1000,11 @@ int vb2_ioctl_remove_bufs(struct file *file, void *priv,
 			  struct v4l2_remove_buffers *d)
 {
 	struct video_device *vdev = video_devdata(file);
+	int res;
 
-	if (vdev->queue->type != d->type)
-		return -EINVAL;
+	res = vb2_verify_memory_type(vdev->queue, vdev->queue->memory, d->type);
+	if (res)
+		return res;
 
 	if (d->count == 0)
 		return 0;
-- 
2.34.1