wireguard: socket: free skb in send6 when ipv6 is disabled

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: wireguard: socket: free skb in send6 when ipv6 is disabled I got a memory leak report: unreferenced object 0xffff8881191fc040 (size 232): comm "kworker/u17:0", pid 23193, jiffies 4295238848 (age 3464.870s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<ffffffff814c3ef4>] slab_post_alloc_hook+0x84/0x3b0 [<ffffffff814c8977>] kmem_cache_alloc_node+0x167/0x340 [<ffffffff832974fb>] __alloc_skb+0x1db/0x200 [<ffffffff82612b5d>] wg_socket_send_buffer_to_peer+0x3d/0xc0 [<ffffffff8260e94a>] wg_packet_send_handshake_initiation+0xfa/0x110 [<ffffffff8260ec81>] wg_packet_handshake_send_worker+0x21/0x30 [<ffffffff8119c558>] process_one_work+0x2e8/0x770 [<ffffffff8119ca2a>] worker_thread+0x4a/0x4b0 [<ffffffff811a88e0>] kthread+0x120/0x160 [<ffffffff8100242f>] ret_from_fork+0x1f/0x30 In function wg_socket_send_buffer_as_reply_to_skb() or wg_socket_send_ buffer_to_peer(), the semantics of send6() is required to free skb. But when CONFIG_IPV6 is disable, kfree_skb() is missing. This patch adds it to fix this bug.

References

• https://git.kernel.org/stable/c/096f9d35cac0a0c95ffafc00db84786b665a4837
• https://git.kernel.org/stable/c/402991a9771587acc2947cf6c4d689c5397f2258
• https://git.kernel.org/stable/c/ebcc492f4ba14bae54b898f1016a37b4282558d1
• https://git.kernel.org/stable/c/0b19bcb753dbfb74710d12bb2761ec5ed706c726
• https://git.kernel.org/stable/c/bbbf962d9460194993ee1943a793a0a0af4a7fbf