linux-kernel - [PATCH 4.4 21/56] uio: potential double frees if __uio_register

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Message-Id: <20180917213828.828840928@linuxfoundation.org>
Date:   Tue, 18 Sep 2018 00:41:54 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.4 21/56] uio: potential double frees if __uio_register_device() fails

4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Dan Carpenter <dan.carpenter@...cle.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@...cle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/uio/uio.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -833,8 +833,6 @@ 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)) {
 		/*
 		 * Note that we deliberately don't use devm_request_irq
@@ -850,6 +848,7 @@ int __uio_register_device(struct module
 			goto err_request_irq;
 	}
 
+	info->uio_dev = idev;
 	return 0;
 
 err_request_irq: