From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) (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 A77EB2BAF3; Fri, 24 May 2024 14:47:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.60.130.6 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716562068; cv=none; b=YELmJhvorgIqei+XFAapYRz7CiM9LV+n2zU7VsVN8e26VAbaR9btHy6vwMUCSw0Uv+VqYPK0LiGqammLAPGP7fwmyEDLdoF9Nequ3a2hwdU+23rCkOMAdfZbHrwwIYsxfjSDphl8o6tI9nVl+YGUnv26FeTAD660ZU6d3azZujQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716562068; c=relaxed/simple; bh=1BYXmgN7udHWcL+OkJLf8ckhKsGB6dLjT7Ru1SeyaY4=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=Jedaq6lrfW5o0dYrjLtF91sFmtkA5Z7nJG50/z1c6aJ5caueLh2dW33vTH+REgBM7Vlp5P/NFi28GIE2o/UuLbxxTMCjmF2ovCML+h34LhvOhbTKMpqGvEIhl5lMZf+Yrwi+sq6ii3hduXhJeHaoK3sHCSjNq9ncz2dCbA+GZNU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=X6b7v7xX; arc=none smtp.client-ip=178.60.130.6 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="X6b7v7xX" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:Message-Id:Date:Subject: Cc:To:From:Sender:Reply-To:Content-Type:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: In-Reply-To:References:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=GAm6SuMCXIOFlOJm80hD0+OtxP9VsZ++oPDngmQ1KLU=; b=X6b7v7xX2Zl1SQRZaUKBDG0t14 gYf0F1qlHvyCxE1urg2qG6EabrbsR1mTl1TWV/+xytzr0BveyxDtsAPYgamZyQlxWSU72kgQokua/ ulCanMjlRpIiAKWEQTAEkEt1xgVuM/eDjfeVjjv8yo+J60idrN7eAKbqbhj/KHoaCcBrNo1plmhrB if8SgBFNyhCF2zs099f5kGYe2Oz48u+ZbH6ngBgsincxdqXkW4y7N8KqbWsNDJhliiDeKW2ItppF3 sAibBKcwMk61Pikwz68lHp9F7AHS92ucRWUwF448bXu2n9d3VMEZfCPY6lI4fkU2BG6AH+zzif34o jkm007ew==; Received: from 179-125-79-244-dinamico.pombonet.net.br ([179.125.79.244] helo=quatroqueijos.lan) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1sAWCk-00C18E-S8; Fri, 24 May 2024 16:47:35 +0200 From: Thadeu Lima de Souza Cascardo To: netdev@vger.kernel.org Cc: Cong Wang , Jakub Sitnicki , Eric Dumazet , Daniel Borkmann , John Fastabend , "David S. Miller" , Jakub Kicinski , Alexei Starovoitov , Paolo Abeni , bpf@vger.kernel.org, kernel-dev@igalia.com, Thadeu Lima de Souza Cascardo , syzbot+07a2e4a1a57118ef7355@syzkaller.appspotmail.com, stable@vger.kernel.org Subject: [PATCH net v2] sock_map: avoid race between sock_map_close and sk_psock_put Date: Fri, 24 May 2024 11:47:02 -0300 Message-Id: <20240524144702.1178377-1-cascardo@igalia.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit sk_psock_get will return NULL if the refcount of psock has gone to 0, which will happen when the last call of sk_psock_put is done. However, sk_psock_drop may not have finished yet, so the close callback will still point to sock_map_close despite psock being NULL. This can be reproduced with a thread deleting an element from the sock map, while the second one creates a socket, adds it to the map and closes it. That will trigger the WARN_ON_ONCE: ------------[ cut here ]------------ WARNING: CPU: 1 PID: 7220 at net/core/sock_map.c:1701 sock_map_close+0x2a2/0x2d0 net/core/sock_map.c:1701 Modules linked in: CPU: 1 PID: 7220 Comm: syz-executor380 Not tainted 6.9.0-syzkaller-07726-g3c999d1ae3c7 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024 RIP: 0010:sock_map_close+0x2a2/0x2d0 net/core/sock_map.c:1701 Code: df e8 92 29 88 f8 48 8b 1b 48 89 d8 48 c1 e8 03 42 80 3c 20 00 74 08 48 89 df e8 79 29 88 f8 4c 8b 23 eb 89 e8 4f 15 23 f8 90 <0f> 0b 90 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d e9 13 26 3d 02 RSP: 0018:ffffc9000441fda8 EFLAGS: 00010293 RAX: ffffffff89731ae1 RBX: ffffffff94b87540 RCX: ffff888029470000 RDX: 0000000000000000 RSI: ffffffff8bcab5c0 RDI: ffffffff8c1faba0 RBP: 0000000000000000 R08: ffffffff92f9b61f R09: 1ffffffff25f36c3 R10: dffffc0000000000 R11: fffffbfff25f36c4 R12: ffffffff89731840 R13: ffff88804b587000 R14: ffff88804b587000 R15: ffffffff89731870 FS: 000055555e080380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000000207d4000 CR4: 0000000000350ef0 Call Trace: unix_release+0x87/0xc0 net/unix/af_unix.c:1048 __sock_release net/socket.c:659 [inline] sock_close+0xbe/0x240 net/socket.c:1421 __fput+0x42b/0x8a0 fs/file_table.c:422 __do_sys_close fs/open.c:1556 [inline] __se_sys_close fs/open.c:1541 [inline] __x64_sys_close+0x7f/0x110 fs/open.c:1541 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb37d618070 Code: 00 00 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d4 e8 10 2c 00 00 80 3d 31 f0 07 00 00 74 17 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c RSP: 002b:00007ffcd4a525d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000003 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fb37d618070 RDX: 0000000000000010 RSI: 00000000200001c0 RDI: 0000000000000004 RBP: 0000000000000000 R08: 0000000100000000 R09: 0000000100000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Use sk_psock, which will only check that the pointer is not been set to NULL yet, which should only happen after the callbacks are restored. If, then, a reference can still be gotten, we may call sk_psock_stop and cancel psock->work. As suggested by Paolo Abeni, reorder the condition so the control flow is less convoluted. After that change, the reproducer does not trigger the WARN_ON_ONCE anymore. Suggested-by: Paolo Abeni Reported-by: syzbot+07a2e4a1a57118ef7355@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=07a2e4a1a57118ef7355 Fixes: aadb2bb83ff7 ("sock_map: Fix a potential use-after-free in sock_map_close()") Fixes: 5b4a79ba65a1 ("bpf, sockmap: Don't let sock_map_{close,destroy,unhash} call itself") Cc: stable@vger.kernel.org Signed-off-by: Thadeu Lima de Souza Cascardo --- v2: change control flow as suggested by Paolo Abeni v1: https://lore.kernel.org/netdev/20240520214153.847619-1-cascardo@igalia.com/ --- net/core/sock_map.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 9402889840bf..c3179567a99a 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -1680,19 +1680,23 @@ void sock_map_close(struct sock *sk, long timeout) lock_sock(sk); rcu_read_lock(); - psock = sk_psock_get(sk); - if (unlikely(!psock)) { - rcu_read_unlock(); - release_sock(sk); - saved_close = READ_ONCE(sk->sk_prot)->close; - } else { + psock = sk_psock(sk); + if (likely(psock)) { saved_close = psock->saved_close; sock_map_remove_links(sk, psock); + psock = sk_psock_get(sk); + if (unlikely(!psock)) + goto no_psock; rcu_read_unlock(); sk_psock_stop(psock); release_sock(sk); cancel_delayed_work_sync(&psock->work); sk_psock_put(sk, psock); + } else { + saved_close = READ_ONCE(sk->sk_prot)->close; +no_psock: + rcu_read_unlock(); + release_sock(sk); } /* Make sure we do not recurse. This is a bug. -- 2.34.1