Commit a535a921 authored by Samuel Page's avatar Samuel Page Committed by Marc Kleine-Budde
Browse files

can: raw: fix ro->uniq use-after-free in raw_rcv() 



raw_release() unregisters raw CAN receive filters via can_rx_unregister(),
but receiver deletion is deferred with call_rcu(). This leaves a window
where raw_rcv() may still be running in an RCU read-side critical section
after raw_release() frees ro->uniq, leading to a use-after-free of the
percpu uniq storage.

Move free_percpu(ro->uniq) out of raw_release() and into a raw-specific
socket destructor. can_rx_unregister() takes an extra reference to the
socket and only drops it from the RCU callback, so freeing uniq from
sk_destruct ensures the percpu area is not released until the relevant
callbacks have drained.

Fixes: 514ac99c ("can: fix multiple delivery of a single CAN frame for overlapping CAN filters")
Cc: stable@vger.kernel.org # v4.1+
Assisted-by: Bynario AI
Signed-off-by: default avatarSamuel Page <sam@bynar.io>
Link: https://patch.msgid.link/26ec626d-cae7-4418-9782-7198864d070c@bynar.io


Acked-by: default avatarOliver Hartkopp <socketcan@hartkopp.net>
[mkl: applied manually]
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent fed46265

net/can/raw.c

+10 −1
Original line number Diff line number Diff line
@@ -361,6 +361,14 @@ static int raw_notifier(struct notifier_block *nb, unsigned long msg, 
	return NOTIFY_DONE;

}



static void raw_sock_destruct(struct sock *sk)

{

	struct raw_sock *ro = raw_sk(sk);



	free_percpu(ro->uniq);

	can_sock_destruct(sk);

}



static int raw_init(struct sock *sk)

{

	struct raw_sock *ro = raw_sk(sk);
@@ -387,6 +395,8 @@ static int raw_init(struct sock *sk) 
	if (unlikely(!ro->uniq))

		return -ENOMEM;



	sk->sk_destruct = raw_sock_destruct;



	/* set notifier */

	spin_lock(&raw_notifier_lock);

	list_add_tail(&ro->notifier, &raw_notifier_list);
@@ -436,7 +446,6 @@ static int raw_release(struct socket *sock) 
	ro->bound = 0;

	ro->dev = NULL;

	ro->count = 0;

	free_percpu(ro->uniq);



	sock_orphan(sk);

	sock->sk = NULL;