Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dan Carpenter <dan.carpenter@oracle.com>,
        Pavel Skripkin <paskripkin@gmail.com>,
        Jesse Brandeburg <jesse.brandeburg@intel.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.4 08/25] net: vxge: fix use-after-free in vxge_device_unregister
Date:   Fri, 13 Aug 2021 17:06:32 +0200
Message-Id: <20210813150520.997995843@linuxfoundation.org>
In-Reply-To: <20210813150520.718161915@linuxfoundation.org>
References: <20210813150520.718161915@linuxfoundation.org>
User-Agent: quilt/0.66
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Pavel Skripkin <paskripkin@gmail.com>

[ Upstream commit 942e560a3d3862dd5dee1411dbdd7097d29b8416 ]

Smatch says:
drivers/net/ethernet/neterion/vxge/vxge-main.c:3518 vxge_device_unregister() error: Using vdev after free_{netdev,candev}(dev);
drivers/net/ethernet/neterion/vxge/vxge-main.c:3518 vxge_device_unregister() error: Using vdev after free_{netdev,candev}(dev);
drivers/net/ethernet/neterion/vxge/vxge-main.c:3520 vxge_device_unregister() error: Using vdev after free_{netdev,candev}(dev);
drivers/net/ethernet/neterion/vxge/vxge-main.c:3520 vxge_device_unregister() error: Using vdev after free_{netdev,candev}(dev);

Since vdev pointer is netdev private data accessing it after free_netdev()
call can cause use-after-free bug. Fix it by moving free_netdev() call at
the end of the function

Fixes: 6cca200362b4 ("vxge: cleanup probe error paths")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/neterion/vxge/vxge-main.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/neterion/vxge/vxge-main.c b/drivers/net/ethernet/neterion/vxge/vxge-main.c
index e0993eba5df3..c6950e580883 100644
--- a/drivers/net/ethernet/neterion/vxge/vxge-main.c
+++ b/drivers/net/ethernet/neterion/vxge/vxge-main.c
@@ -3539,13 +3539,13 @@ static void vxge_device_unregister(struct __vxge_hw_device *hldev)
 
 	kfree(vdev->vpaths);
 
-	/* we are safe to free it now */
-	free_netdev(dev);
-
 	vxge_debug_init(vdev->level_trace, "%s: ethernet device unregistered",
 			buf);
 	vxge_debug_entryexit(vdev->level_trace,	"%s: %s:%d  Exiting...", buf,
 			     __func__, __LINE__);
+
+	/* we are safe to free it now */
+	free_netdev(dev);
 }
 
 /*
-- 
2.30.2