linux-kernel - [PATCH v3] virtio: reject shm region if length is zero

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Message-Id: <20250511222153.2332-1-sami.md.ko@gmail.com>
Date: Mon, 12 May 2025 07:51:53 +0930
From: Sami@....codeaurora.org, Uddin@....codeaurora.org,
	sami.md.ko@...il.com
To: mst@...hat.com
Cc: jasowang@...hat.com,
	xuanzhuo@...ux.alibaba.com,
	eperezma@...hat.com,
	virtualization@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Sami Uddin <sami.md.ko@...il.com>
Subject: [PATCH v3] virtio: reject shm region if length is zero

From: Sami Uddin <sami.md.ko@...il.com>

Prevent usage of shared memory regions where the length is zero,
as such configurations are not valid and may lead to unexpected behavior.

Signed-off-by: Sami Uddin <sami.md.ko@...il.com>
---
v3:
- Use idiomatic 'if (!region->len)' as suggested by reviewer
v2:
- Fixed coding style issue: added space after 'if' statement

 include/linux/virtio_config.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 169c7d367fac..b3e1d30c765b 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -329,6 +329,8 @@ static inline
 bool virtio_get_shm_region(struct virtio_device *vdev,
 			   struct virtio_shm_region *region, u8 id)
 {
+	if (!region->len)
+		return false;
 	if (!vdev->config->get_shm_region)
 		return false;
 	return vdev->config->get_shm_region(vdev, region, id);
-- 
2.34.1