netdev - [net 1/3] can: dev: can_restart: fix use after free bug

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

Message-Id: <20210120125202.2187358-2-mkl@pengutronix.de>
Date:   Wed, 20 Jan 2021 13:52:00 +0100
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, linux-can@...r.kernel.org,
        kernel@...gutronix.de,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>,
        Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [net 1/3] can: dev: can_restart: fix use after free bug

From: Vincent Mailhol <mailhol.vincent@...adoo.fr>

After calling netif_rx_ni(skb), dereferencing skb is unsafe.
Especially, the can_frame cf which aliases skb memory is accessed
after the netif_rx_ni() in:
      stats->rx_bytes += cf->len;

Reordering the lines solves the issue.

Fixes: 39549eef3587 ("can: CAN Network device driver and Netlink interface")
Link: https://lore.kernel.org/r/20210120114137.200019-2-mailhol.vincent@wanadoo.fr
Signed-off-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/dev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index 3486704c8a95..8b1ae023cb21 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -592,11 +592,11 @@ static void can_restart(struct net_device *dev)
 
 	cf->can_id |= CAN_ERR_RESTARTED;
 
-	netif_rx_ni(skb);
-
 	stats->rx_packets++;
 	stats->rx_bytes += cf->len;
 
+	netif_rx_ni(skb);
+
 restart:
 	netdev_dbg(dev, "restarted\n");
 	priv->can_stats.restarts++;

base-commit: 9c30ae8398b0813e237bde387d67a7f74ab2db2d
-- 
2.29.2