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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     Dan Carpenter <dan.carpenter@oracle.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL 4.18 029/131] uio: potential double frees if
 __uio_register_device() fails
Thread-Topic: [PATCH AUTOSEL 4.18 029/131] uio: potential double frees if
 __uio_register_device() fails
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Date:   Sun, 2 Sep 2018 13:03:34 +0000
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From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit f019f07ecf6a6b8bd6d7853bce70925d90af02d1 ]

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: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/uio/uio.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index f68c1121fa7c..c8c76a0c6107 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -955,8 +955,6 @@ int __uio_register_device(struct module *owner,
 	if (ret)
 		goto err_uio_dev_add_attributes;
=20
-	info->uio_dev =3D idev;
-
 	if (info->irq && (info->irq !=3D UIO_IRQ_CUSTOM)) {
 		/*
 		 * Note that we deliberately don't use devm_request_irq
@@ -972,6 +970,7 @@ int __uio_register_device(struct module *owner,
 			goto err_request_irq;
 	}
=20
+	info->uio_dev =3D idev;
 	return 0;
=20
 err_request_irq:
--=20
2.17.1