linux-kernel - [PATCH 5.17 1016/1126] wireguard: queueing: use CFI-safe ptr

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Date:   Tue,  5 Apr 2022 09:29:23 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, PaX Team <pageexec@...email.hu>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH 5.17 1016/1126] wireguard: queueing: use CFI-safe ptr_ring cleanup function

From: Jason A. Donenfeld <Jason@...c4.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@...email.hu>
Fixes: 886fcee939ad ("wireguard: receive: use ring buffer for incoming handshakes")
Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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)