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can: dev: can_restart: fix use after free bug

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[ Upstream commit 03f16c5075b22c8902d2af739969e878b0879c94 ]

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@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Vincent Mailhol 2021-01-20 20:41:35 +09:00 committed by Greg Kroah-Hartman
parent 3d6327020b
commit 08ab951787
1 changed files with 2 additions and 2 deletions

4
drivers/net/can/dev.c

@ -579,11 +579,11 @@ 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->can_dlc;
netif_rx_ni(skb);
restart:
netdev_dbg(dev, "restarted\n");
priv->can_stats.restarts++;