From patchwork Fri May 10 09:39:05 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kuniyuki Iwashima X-Patchwork-Id: 13661186 X-Patchwork-Delegate: kuba@kernel.org Received: from smtp-fw-52005.amazon.com (smtp-fw-52005.amazon.com [52.119.213.156]) (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 C8A7F79945 for ; Fri, 10 May 2024 09:39:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=52.119.213.156 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715333965; cv=none; b=iWi4zu/DYfhsQMDkgGo1/VnJF5mBBx9UEtIbRMwF6X/4pYdxd7jkbj36PI2Fau7GScFZgMtOeKwIS/lKkqw6O3tOhgxHrhZJnR8E5PT6v5vNxMXaO5UEi4OpRlizi7l9R6gz39fzri/nlQuHO0lAvyQamtFJE/XnW/N7iqoH5Pw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715333965; c=relaxed/simple; bh=aUC9WY9L673XexnT/sMq0U/3yMHh03s1b+2kjzlvG2k=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=l1H1FX+XQ0Mn6rIXh4PzUuZZ1kuCi6GPpA0xjys65pe6+jIV5DzDOHysTDeA6ZXBMAsJblkjdEX/8KsENZFBPmHpLYUhPU2Wquoqt4plOIWdqZtwCi3fWSnMlXF7uVlC80ksVNB7N0598I+KIk2xxdhD012Cx4axJQGHpDyExIc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.co.jp; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b=FYvNigRk; arc=none smtp.client-ip=52.119.213.156 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.co.jp Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="FYvNigRk" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1715333965; x=1746869965; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=DCmyurp3HT6tozvqW7aDfi87dDIz82X35+QOhDRnaHs=; b=FYvNigRkouzrajXu7AOEGSsn3nAkRQJdaEfiQwGkvyuxT4wQ4K5NSCQv UMR0J/Ybrk2hFhV36BwQxCckNCEaVLVcYRk76fkdnK/Wk6jSk1rC0fJsH c9Hnvt0PHdBBuXAbfenmHP+zLcqKvyUPlfRXMkiFP+3lAnJpmyHBOSKEm w=; X-IronPort-AV: E=Sophos;i="6.08,150,1712620800"; d="scan'208";a="653343152" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO smtpout.prod.us-west-2.prod.farcaster.email.amazon.dev) ([10.43.8.6]) by smtp-border-fw-52005.iad7.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 May 2024 09:39:22 +0000 Received: from EX19MTAUWB001.ant.amazon.com [10.0.7.35:32365] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.29.186:2525] with esmtp (Farcaster) id 98de88ca-c8e7-445c-b16f-9e6f7edce709; Fri, 10 May 2024 09:39:20 +0000 (UTC) X-Farcaster-Flow-ID: 98de88ca-c8e7-445c-b16f-9e6f7edce709 Received: from EX19D004ANA001.ant.amazon.com (10.37.240.138) by EX19MTAUWB001.ant.amazon.com (10.250.64.248) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.28; Fri, 10 May 2024 09:39:20 +0000 Received: from 88665a182662.ant.amazon.com (10.119.9.22) by EX19D004ANA001.ant.amazon.com (10.37.240.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.28; Fri, 10 May 2024 09:39:16 +0000 From: Kuniyuki Iwashima To: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni CC: Kuniyuki Iwashima , Kuniyuki Iwashima , , Billy Jheng Bing-Jhong Subject: [PATCH v2 net] af_unix: Update unix_sk(sk)->oob_skb under sk_receive_queue lock. Date: Fri, 10 May 2024 18:39:05 +0900 Message-ID: <20240510093905.25510-1-kuniyu@amazon.com> X-Mailer: git-send-email 2.30.2 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: EX19D046UWB003.ant.amazon.com (10.13.139.174) To EX19D004ANA001.ant.amazon.com (10.37.240.138) X-Patchwork-Delegate: kuba@kernel.org Billy Jheng Bing-Jhong reported a race between __unix_gc() and queue_oob(). __unix_gc() tries to garbage-collect close()d inflight sockets, and then if the socket has MSG_OOB in unix_sk(sk)->oob_skb, GC will drop the reference and set NULL to it locklessly. However, the peer socket still can send MSG_OOB message and queue_oob() can update unix_sk(sk)->oob_skb concurrently, leading NULL pointer dereference. [0] To fix the issue, let's update unix_sk(sk)->oob_skb under the sk_receive_queue's lock and take it everywhere we touch oob_skb. Note that the same issue exists in the new GC, and the change in queue_oob() can be applied as is. [0]: BUG: kernel NULL pointer dereference, address: 0000000000000008 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 8000000009f5e067 P4D 8000000009f5e067 PUD 9f5d067 PMD 0 Oops: 0002 [#1] PREEMPT SMP PTI CPU: 3 PID: 50 Comm: kworker/3:1 Not tainted 6.9.0-rc5-00191-gd091e579b864 #110 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 Workqueue: events delayed_fput RIP: 0010:skb_dequeue (./include/linux/skbuff.h:2386 ./include/linux/skbuff.h:2402 net/core/skbuff.c:3847) Code: 39 e3 74 3e 8b 43 10 48 89 ef 83 e8 01 89 43 10 49 8b 44 24 08 49 c7 44 24 08 00 00 00 00 49 8b 14 24 49 c7 04 24 00 00 00 00 <48> 89 42 08 48 89 10 e8 e7 c5 42 00 4c 89 e0 5b 5d 41 5c c3 cc cc RSP: 0018:ffffc900001bfd48 EFLAGS: 00000002 RAX: 0000000000000000 RBX: ffff8880088f5ae8 RCX: 00000000361289f9 RDX: 0000000000000000 RSI: 0000000000000206 RDI: ffff8880088f5b00 RBP: ffff8880088f5b00 R08: 0000000000080000 R09: 0000000000000001 R10: 0000000000000003 R11: 0000000000000001 R12: ffff8880056b6a00 R13: ffff8880088f5280 R14: 0000000000000001 R15: ffff8880088f5a80 FS: 0000000000000000(0000) GS:ffff88807dd80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000008 CR3: 0000000006314000 CR4: 00000000007506f0 PKRU: 55555554 Call Trace: unix_release_sock (net/unix/af_unix.c:654) unix_release (net/unix/af_unix.c:1050) __sock_release (net/socket.c:660) sock_close (net/socket.c:1423) __fput (fs/file_table.c:423) delayed_fput (fs/file_table.c:444 (discriminator 3)) process_one_work (kernel/workqueue.c:3259) worker_thread (kernel/workqueue.c:3329 kernel/workqueue.c:3416) kthread (kernel/kthread.c:388) ret_from_fork (arch/x86/kernel/process.c:153) ret_from_fork_asm (arch/x86/entry/entry_64.S:257) Modules linked in: CR2: 0000000000000008 Fixes: 1279f9d9dec2 ("af_unix: Call kfree_skb() for dead unix_(sk)->oob_skb in GC.") Reported-by: Billy Jheng Bing-Jhong Signed-off-by: Kuniyuki Iwashima Acked-by: Paolo Abeni --- v2: * Add recvq locking everywhere we touch oob_skb (Paolo) v1: https://lore.kernel.org/netdev/20240507170018.83385-1-kuniyu@amazon.com/ --- net/unix/af_unix.c | 18 ++++++++++++++---- net/unix/garbage.c | 4 +++- 2 files changed, 17 insertions(+), 5 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 9a6ad5974dff..c555464cf1fb 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2217,13 +2217,15 @@ static int queue_oob(struct socket *sock, struct msghdr *msg, struct sock *other maybe_add_creds(skb, sock, other); skb_get(skb); + scm_stat_add(other, skb); + + spin_lock(&other->sk_receive_queue.lock); if (ousk->oob_skb) consume_skb(ousk->oob_skb); - WRITE_ONCE(ousk->oob_skb, skb); + __skb_queue_tail(&other->sk_receive_queue, skb); + spin_unlock(&other->sk_receive_queue.lock); - scm_stat_add(other, skb); - skb_queue_tail(&other->sk_receive_queue, skb); sk_send_sigurg(other); unix_state_unlock(other); other->sk_data_ready(other); @@ -2614,8 +2616,10 @@ static int unix_stream_recv_urg(struct unix_stream_read_state *state) mutex_lock(&u->iolock); unix_state_lock(sk); + spin_lock(&sk->sk_receive_queue.lock); if (sock_flag(sk, SOCK_URGINLINE) || !u->oob_skb) { + spin_unlock(&sk->sk_receive_queue.lock); unix_state_unlock(sk); mutex_unlock(&u->iolock); return -EINVAL; @@ -2627,6 +2631,8 @@ static int unix_stream_recv_urg(struct unix_stream_read_state *state) WRITE_ONCE(u->oob_skb, NULL); else skb_get(oob_skb); + + spin_unlock(&sk->sk_receive_queue.lock); unix_state_unlock(sk); chunk = state->recv_actor(oob_skb, 0, chunk, state); @@ -2655,6 +2661,8 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk, consume_skb(skb); skb = NULL; } else { + spin_lock(&sk->sk_receive_queue.lock); + if (skb == u->oob_skb) { if (copied) { skb = NULL; @@ -2666,13 +2674,15 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk, } else if (flags & MSG_PEEK) { skb = NULL; } else { - skb_unlink(skb, &sk->sk_receive_queue); + __skb_unlink(skb, &sk->sk_receive_queue); WRITE_ONCE(u->oob_skb, NULL); if (!WARN_ON_ONCE(skb_unref(skb))) kfree_skb(skb); skb = skb_peek(&sk->sk_receive_queue); } } + + spin_unlock(&sk->sk_receive_queue.lock); } return skb; } diff --git a/net/unix/garbage.c b/net/unix/garbage.c index 0104be9d4704..b87e48e2b51b 100644 --- a/net/unix/garbage.c +++ b/net/unix/garbage.c @@ -342,10 +342,12 @@ static void __unix_gc(struct work_struct *work) scan_children(&u->sk, inc_inflight, &hitlist); #if IS_ENABLED(CONFIG_AF_UNIX_OOB) + spin_lock(&u->sk.sk_receive_queue.lock); if (u->oob_skb) { - kfree_skb(u->oob_skb); + WARN_ON_ONCE(skb_unref(u->oob_skb)); u->oob_skb = NULL; } + spin_unlock(&u->sk.sk_receive_queue.lock); #endif }