From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 473EF3D8125; Wed, 8 Apr 2026 18:31:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775673060; cv=none; b=qCQDa6BUY5wJA6EaNcCfGCTIVW9pJORhMQYQKWZ2mxvWZ3LMD8pnJXpKZWtmg+6gzzSzytlqix6WC/rkPLI9FAnMd6O5CClny5J2BMW81BKCOchKlpMc9XNHAM5mtShbb8UJey+ofKuFpZ7EnwjysKb0MyAkXmyGjxWgKuhj0Y0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775673060; c=relaxed/simple; bh=41u6ZTjVE0BToI8J+x4MXtJsGe3rPHQPycWXm68Jo6k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=G/Qb1UCC90rUjzzs8YSkAlknJYeIgBeTYdPHsjp7BZ7dVc1jSjCPAFaKyZhOEHrUV56ymCPKTI1UpwqEtH7CAWojhvjEdwzKZxvS8viTIpEcYxUMvNodRHEV+IEPFjVdcUD+vvyg20m131JI00kDox2mf2HCPY9lJOObtxlslf4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=QmDUqQWg; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="QmDUqQWg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B8A89C19421; Wed, 8 Apr 2026 18:30:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1775673060; bh=41u6ZTjVE0BToI8J+x4MXtJsGe3rPHQPycWXm68Jo6k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QmDUqQWgTckyffi0v7YCiYRaoeuGPBe0mRdTdW/KTVYURpoXdPWOHl/5s47hFTC8J iqa74MCYYJnGFEZWAXWh9MMLuuq1Xj+7/3XJ/oTW0XC2ptACgIEK/ikaJqQOXyLY1a 8oqOqZ4F4BWPssMZWLkN6Aodm+1NLLRtPHA+/5Fk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+2184232f07e3677fbaef@syzkaller.appspotmail.com, Kuniyuki Iwashima , Martin KaFai Lau , Jiayuan Chen , Sasha Levin Subject: [PATCH 6.18 086/277] bpf: sockmap: Fix use-after-free of sk->sk_socket in sk_psock_verdict_data_ready(). Date: Wed, 8 Apr 2026 20:01:11 +0200 Message-ID: <20260408175937.075686950@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260408175933.836769063@linuxfoundation.org> References: <20260408175933.836769063@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuniyuki Iwashima [ Upstream commit ad8391d37f334ee73ba91926f8b4e4cf6d31ea04 ] syzbot reported use-after-free of AF_UNIX socket's sk->sk_socket in sk_psock_verdict_data_ready(). [0] In unix_stream_sendmsg(), the peer socket's ->sk_data_ready() is called after dropping its unix_state_lock(). Although the sender socket holds the peer's refcount, it does not prevent the peer's sock_orphan(), and the peer's sk_socket might be freed after one RCU grace period. Let's fetch the peer's sk->sk_socket and sk->sk_socket->ops under RCU in sk_psock_verdict_data_ready(). [0]: BUG: KASAN: slab-use-after-free in sk_psock_verdict_data_ready+0xec/0x590 net/core/skmsg.c:1278 Read of size 8 at addr ffff8880594da860 by task syz.4.1842/11013 CPU: 1 UID: 0 PID: 11013 Comm: syz.4.1842 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xba/0x230 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 sk_psock_verdict_data_ready+0xec/0x590 net/core/skmsg.c:1278 unix_stream_sendmsg+0x8a3/0xe80 net/unix/af_unix.c:2482 sock_sendmsg_nosec net/socket.c:721 [inline] __sock_sendmsg net/socket.c:736 [inline] ____sys_sendmsg+0x972/0x9f0 net/socket.c:2585 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2639 __sys_sendmsg net/socket.c:2671 [inline] __do_sys_sendmsg net/socket.c:2676 [inline] __se_sys_sendmsg net/socket.c:2674 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2674 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7facf899c819 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007facf9827028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007facf8c15fa0 RCX: 00007facf899c819 RDX: 0000000000000000 RSI: 0000200000000500 RDI: 0000000000000004 RBP: 00007facf8a32c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007facf8c16038 R14: 00007facf8c15fa0 R15: 00007ffd41b01c78 Allocated by task 11013: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4538 [inline] slab_alloc_node mm/slub.c:4866 [inline] kmem_cache_alloc_lru_noprof+0x2b8/0x640 mm/slub.c:4885 sock_alloc_inode+0x28/0xc0 net/socket.c:316 alloc_inode+0x6a/0x1b0 fs/inode.c:347 new_inode_pseudo include/linux/fs.h:3003 [inline] sock_alloc net/socket.c:631 [inline] __sock_create+0x12d/0x9d0 net/socket.c:1562 sock_create net/socket.c:1656 [inline] __sys_socketpair+0x1c4/0x560 net/socket.c:1803 __do_sys_socketpair net/socket.c:1856 [inline] __se_sys_socketpair net/socket.c:1853 [inline] __x64_sys_socketpair+0x9b/0xb0 net/socket.c:1853 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 15: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2685 [inline] slab_free mm/slub.c:6165 [inline] kmem_cache_free+0x187/0x630 mm/slub.c:6295 rcu_do_batch kernel/rcu/tree.c:2617 [inline] rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869 handle_softirqs+0x22a/0x870 kernel/softirq.c:622 run_ksoftirqd+0x36/0x60 kernel/softirq.c:1063 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Fixes: c63829182c37 ("af_unix: Implement ->psock_update_sk_prot()") Closes: https://lore.kernel.org/bpf/69cc6b9f.a70a0220.128fd0.004b.GAE@google.com/ Reported-by: syzbot+2184232f07e3677fbaef@syzkaller.appspotmail.com Signed-off-by: Kuniyuki Iwashima Signed-off-by: Martin KaFai Lau Reviewed-by: Jiayuan Chen Link: https://patch.msgid.link/20260401005418.2452999-1-kuniyu@google.com Signed-off-by: Sasha Levin --- net/core/skmsg.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/net/core/skmsg.c b/net/core/skmsg.c index 12fbb0545c712..35a6acbf9a579 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -1267,17 +1267,20 @@ static int sk_psock_verdict_recv(struct sock *sk, struct sk_buff *skb) static void sk_psock_verdict_data_ready(struct sock *sk) { - struct socket *sock = sk->sk_socket; - const struct proto_ops *ops; + const struct proto_ops *ops = NULL; + struct socket *sock; int copied; trace_sk_data_ready(sk); - if (unlikely(!sock)) - return; - ops = READ_ONCE(sock->ops); + rcu_read_lock(); + sock = READ_ONCE(sk->sk_socket); + if (likely(sock)) + ops = READ_ONCE(sock->ops); + rcu_read_unlock(); if (!ops || !ops->read_skb) return; + copied = ops->read_skb(sk, sk_psock_verdict_recv); if (copied >= 0) { struct sk_psock *psock; -- 2.53.0