linux-kernel - [PATCH v2] uio: Fix uio driver to refcount device

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Message-ID: <5502B93A.6090506@brocade.com>
Date:	Fri, 13 Mar 2015 10:17:30 +0000
From:	Brian Russell <brian.russell@...cade.com>
To:	"Hans J. Koch" <hjk@...sjkoch.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:	<linux-kernel@...r.kernel.org>
Subject: [PATCH v2] uio: Fix uio driver to refcount device

Protect uio driver from crashing if its owner is hot unplugged while there
are open fds.

Signed-off-by: Brian Russell <brussell@...cade.com>
---
 drivers/uio/uio.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 6276f13..70ce015 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -434,9 +434,11 @@ static int uio_open(struct inode *inode, struct file *filep)
 		goto out;
 	}
 
+	get_device(idev);
+
 	if (!try_module_get(idev->owner)) {
 		ret = -ENODEV;
-		goto out;
+		goto err_module_get;
 	}
 
 	listener = kmalloc(sizeof(*listener), GFP_KERNEL);
@@ -462,6 +464,9 @@ err_infoopen:
 err_alloc_listener:
 	module_put(idev->owner);
 
+err_module_get:
+	put_device(idev);
+
 out:
 	return ret;
 }
@@ -485,6 +490,7 @@ static int uio_release(struct inode *inode, struct file *filep)
 
 	module_put(idev->owner);
 	kfree(listener);
+	put_device(idev);
 	return ret;
 }
 
-- 
2.1.4
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