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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        "Dan Carpenter" <dan.carpenter@oracle.com>,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>
Date:   Sun, 09 Dec 2018 21:50:33 +0000
Message-ID: <lsq.1544392233.800582261@decadent.org.uk>
Subject: [PATCH 3.16 095/328] uio: potential double frees if
 __uio_register_device() fails
In-Reply-To: <lsq.1544392232.713909046@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

3.16.62-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@oracle.com>

commit f019f07ecf6a6b8bd6d7853bce70925d90af02d1 upstream.

The uio_unregister_device() function assumes that if "info->uio_dev" is
non-NULL that means "info" is fully allocated.  Setting info->uio_de
has to be the last thing in the function.

In the current code, if request_threaded_irq() fails then we return with
info->uio_dev set to non-NULL but info is not fully allocated and it can
lead to double frees.

Fixes: beafc54c4e2f ("UIO: Add the User IO core code")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/uio/uio.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -852,8 +852,6 @@ int __uio_register_device(struct module
 	if (ret)
 		goto err_uio_dev_add_attributes;
 
-	info->uio_dev = idev;
-
 	if (info->irq && (info->irq != UIO_IRQ_CUSTOM)) {
 		ret = devm_request_irq(idev->dev, info->irq, uio_interrupt,
 				  info->irq_flags, info->name, idev);
@@ -861,6 +859,7 @@ int __uio_register_device(struct module
 			goto err_request_irq;
 	}
 
+	info->uio_dev = idev;
 	return 0;
 
 err_request_irq: