[PATCH 6.6 068/166] can: raw: fix ro->uniq use-after-free in raw_rcv()

Greg Kroah-Hartman
2026-04-24T13:36:25Z

From: Samuel Page <sam@bynar.io>

commit a535a9217ca3f2fccedaafb2fddb4c48f27d36dc upstream.

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: 514ac99c64b2 ("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: Samuel Page <sam@bynar.io>
Link: https://patch.msgid.link/26ec626d-cae7-4418-9782-7198864d070c@bynar.io
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
[mkl: applied manually]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/can/raw.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -336,6 +336,14 @@ static int raw_notifier(struct notifier_
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);
@@ -362,6 +370,8 @@ 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);
@@ -409,7 +419,6 @@ static int raw_release(struct socket *so
ro->bound = 0;
ro->dev = NULL;
ro->count = 0;
- free_percpu(ro->uniq);

sock_orphan(sk);
sock->sk = NULL;