netdev - [PATCH net 1/4] wireguard: queueing: use CFI-safe ptr

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Date:   Tue, 29 Mar 2022 21:31:24 -0400
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org
Cc:     "Jason A. Donenfeld" <Jason@...c4.com>,
        PaX Team <pageexec@...email.hu>, stable@...r.kernel.org
Subject: [PATCH net 1/4] wireguard: queueing: use CFI-safe ptr_ring cleanup function

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@...email.hu>
Fixes: 886fcee939ad ("wireguard: receive: use ring buffer for incoming handshakes")
Cc: stable@...r.kernel.org
Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
---
 drivers/net/wireguard/queueing.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireguard/queueing.c b/drivers/net/wireguard/queueing.c
index 1de413b19e34..8084e7408c0a 100644
--- 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_queue *queue, bool purge)
 {
 	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)
-- 
2.35.1