netdev - [PATCH net v2] net: qualcomm: rmnet: Fix potential UAF when unregistering

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1572915262-19149-1-git-send-email-stranche@codeaurora.org>
Date:   Mon,  4 Nov 2019 17:54:22 -0700
From:   Sean Tranchetti <stranche@...eaurora.org>
To:     davem@...emloft.net, netdev@...r.kernel.org
Cc:     Sean Tranchetti <stranche@...eaurora.org>
Subject: [PATCH net v2] net: qualcomm: rmnet: Fix potential UAF when unregistering

During the exit/unregistration process of the RmNet driver, the function
rmnet_unregister_real_device() is called to handle freeing the driver's
internal state and removing the RX handler on the underlying physical
device. However, the order of operations this function performs is wrong
and can lead to a use after free of the rmnet_port structure.

Before calling netdev_rx_handler_unregister(), this port structure is
freed with kfree(). If packets are received on any RmNet devices before
synchronize_net() completes, they will attempt to use this already-freed
port structure when processing the packet. As such, before cleaning up any
other internal state, the RX handler must be unregistered in order to
guarantee that no further packets will arrive on the device.

Fixes: ceed73a2cf4a ("drivers: net: ethernet: qualcomm: rmnet: Initial implementation")
Signed-off-by: Sean Tranchetti <stranche@...eaurora.org>
---
 v1 -> v2: Added missing Fixes tag
 drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
index 9c54b71..06de595 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
@@ -57,10 +57,10 @@ static int rmnet_unregister_real_device(struct net_device *real_dev,
 	if (port->nr_rmnet_devs)
 		return -EINVAL;

-	kfree(port);
-
 	netdev_rx_handler_unregister(real_dev);

+	kfree(port);
+
 	/* release reference on real_dev */
 	dev_put(real_dev);

-- 
1.9.1