[PATCH 5.16 0919/1017] wireguard: queueing: use CFI-safe ptr_ring cleanup function

Greg Kroah-Hartman
2022-04-05T10:17:53Z

From: Jason A. Donenfeld <Jason@zx2c4.com>

commit ec59f128a9bd4255798abb1e06ac3b442f46ef68 upstream.

We make too nuanced use of ptr_ring to entirely move to the skb_array
wrappers, but we at least should avoid the naughty function pointer cast
when cleaning up skbs. Otherwise RAP/CFI will honk at us. This patch
uses the __skb_array_destroy_skb wrapper for the cleanup, rather than
directly providing kfree_skb, which is what other drivers in the same
situation do too.

Reported-by: PaX Team <pageexec@freemail.hu>
Fixes: 886fcee939ad ("wireguard: receive: use ring buffer for incoming handshakes")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/wireguard/queueing.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/wireguard/queueing.c
+++ b/drivers/net/wireguard/queueing.c
@@ -4,6 +4,7 @@
*/

#include "queueing.h"
+#include <linux/skb_array.h>

struct multicore_worker __percpu *
wg_packet_percpu_multicore_worker_alloc(work_func_t function, void *ptr)
@@ -42,7 +43,7 @@ void wg_packet_queue_free(struct crypt_q
{
free_percpu(queue->worker);
WARN_ON(!purge && !__ptr_ring_empty(&queue->ring));
- ptr_ring_cleanup(&queue->ring, purge ? (void(*)(void*))kfree_skb : NULL);
+ ptr_ring_cleanup(&queue->ring, purge ? __skb_array_destroy_skb : NULL);
}

#define NEXT(skb) ((skb)->prev)