[PATCH 4.9 09/30] net: vxge: fix use-after-free in vxge_device_unregister

Greg Kroah-Hartman
2021-08-13T15:10:44Z

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