linux-kernel - [PATCH v2] um: virtio_uml: Fix use-after-free after put

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Message-Id: <20250828070052.23606-1-linmq006@gmail.com>
Date: Thu, 28 Aug 2025 15:00:51 +0800
From: Miaoqian Lin <linmq006@...il.com>
To: Richard Weinberger <richard@....at>,
	Anton Ivanov <anton.ivanov@...bridgegreys.com>,
	Johannes Berg <johannes@...solutions.net>,
	Benjamin Berg <benjamin.berg@...el.com>,
	Tiwei Bie <tiwei.btw@...group.com>,
	linux-um@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Cc: linmq006@...il.com
Subject: [PATCH v2] um: virtio_uml: Fix use-after-free after put_device in probe

When register_virtio_device() fails in virtio_uml_probe(),
the code sets vu_dev->registered = 1 even though
the device was not successfully registered.
This can lead to use-after-free or other issues.

Fixes: 04e5b1fb0183 ("um: virtio: Remove device on disconnect")
Signed-off-by: Miaoqian Lin <linmq006@...il.com>
---
changes in v2:
- statically 'return 0' in the normal path.
- v1 link: https://lore.kernel.org/all/20250804075944.3612712-1-linmq006@gmail.com/
---
 arch/um/drivers/virtio_uml.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c
index ad8d78fb1d9a..de7867ae220d 100644
--- a/arch/um/drivers/virtio_uml.c
+++ b/arch/um/drivers/virtio_uml.c
@@ -1250,10 +1250,12 @@ static int virtio_uml_probe(struct platform_device *pdev)
 	device_set_wakeup_capable(&vu_dev->vdev.dev, true);
 
 	rc = register_virtio_device(&vu_dev->vdev);
-	if (rc)
+	if (rc) {
 		put_device(&vu_dev->vdev.dev);
+		return rc;
+	}
 	vu_dev->registered = 1;
-	return rc;
+	return 0;
 
 error_init:
 	os_close_file(vu_dev->sock);
-- 
2.39.5 (Apple Git-154)