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 3F13919B3D4; Thu, 6 Jun 2024 14:11:01 +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=1717683061; cv=none; b=FDUWsxiOjFSZY7XWk6ACR3t9z04htsp9iqk0Fn0oI6dhicw0Fe2s5AiPnqXnB5DcfQSRVX2NI8GuQfEE6kSsWG3LRYanVabG9gwgPPjjDz519HJT0LO8hHmJEB7QLrIOOtrV9tnvs7SZRwOieY8Iz2HZuOfRhGMkq8EYMZHKrCA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717683061; c=relaxed/simple; bh=sQR78fIzsJ5c17HliJ0aC0a4mo1JNwHSyoHR0dGX+WA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZwHWpz+771SdK2rfpFqCE5EDnK9ktqeyGF8p5S8jODn0pIISuW8viBZ+HFNVsXLFo60qu1YkhqpskAcv6DoGjk76+LHz/DFOwndQnjjhOHjMtEjE7SFwl8aMdHsBEAzBgN9A3G05THDxU5aApZVB285/l/YzUwaNkt5rHmwlPtU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=L5BAAY6Z; 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="L5BAAY6Z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1C83EC4AF16; Thu, 6 Jun 2024 14:11:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1717683061; bh=sQR78fIzsJ5c17HliJ0aC0a4mo1JNwHSyoHR0dGX+WA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L5BAAY6ZkUQRwkpTtRiKOSEVXFWR9f/fvxY/We8PPAEJseUULU4WvA1OCNDk7Q4Q1 bpeA7dfUUtTfbXBwkowpLEjLCTXj76gRqPrIi/7l+RJulF/vqPVjIpHiD+L+352Ay6 I+ZHftAbwWPFenw74X3BHwlz2DDj0mu4IchDcfck= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzkaller , Kuniyuki Iwashima , Paolo Abeni , Sasha Levin Subject: [PATCH 6.9 310/374] af_unix: Annotate data-race around unix_sk(sk)->addr. Date: Thu, 6 Jun 2024 16:04:49 +0200 Message-ID: <20240606131702.237833729@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240606131651.683718371@linuxfoundation.org> References: <20240606131651.683718371@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuniyuki Iwashima [ Upstream commit 97e1db06c7bb948da10ba85acad8030b56886593 ] Once unix_sk(sk)->addr is assigned under net->unx.table.locks and unix_sk(sk)->bindlock, *(unix_sk(sk)->addr) and unix_sk(sk)->path are fully set up, and unix_sk(sk)->addr is never changed. unix_getname() and unix_copy_addr() access the two fields locklessly, and commit ae3b564179bf ("missing barriers in some of unix_sock ->addr and ->path accesses") added smp_store_release() and smp_load_acquire() pairs. In other functions, we still read unix_sk(sk)->addr locklessly to check if the socket is bound, and KCSAN complains about it. [0] Given these functions have no dependency for *(unix_sk(sk)->addr) and unix_sk(sk)->path, READ_ONCE() is enough to annotate the data-race. Note that it is safe to access unix_sk(sk)->addr locklessly if the socket is found in the hash table. For example, the lockless read of otheru->addr in unix_stream_connect() is safe. Note also that newu->addr there is of the child socket that is still not accessible from userspace, and smp_store_release() publishes the address in case the socket is accept()ed and unix_getname() / unix_copy_addr() is called. [0]: BUG: KCSAN: data-race in unix_bind / unix_listen write (marked) to 0xffff88805f8d1840 of 8 bytes by task 13723 on cpu 0: __unix_set_addr_hash net/unix/af_unix.c:329 [inline] unix_bind_bsd net/unix/af_unix.c:1241 [inline] unix_bind+0x881/0x1000 net/unix/af_unix.c:1319 __sys_bind+0x194/0x1e0 net/socket.c:1847 __do_sys_bind net/socket.c:1858 [inline] __se_sys_bind net/socket.c:1856 [inline] __x64_sys_bind+0x40/0x50 net/socket.c:1856 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x4f/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x46/0x4e read to 0xffff88805f8d1840 of 8 bytes by task 13724 on cpu 1: unix_listen+0x72/0x180 net/unix/af_unix.c:734 __sys_listen+0xdc/0x160 net/socket.c:1881 __do_sys_listen net/socket.c:1890 [inline] __se_sys_listen net/socket.c:1888 [inline] __x64_sys_listen+0x2e/0x40 net/socket.c:1888 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x4f/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x46/0x4e value changed: 0x0000000000000000 -> 0xffff88807b5b1b40 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 13724 Comm: syz-executor.4 Not tainted 6.8.0-12822-gcd51db110a7e #12 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzkaller Signed-off-by: Kuniyuki Iwashima Link: https://lore.kernel.org/r/20240522154002.77857-1-kuniyu@amazon.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/unix/af_unix.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 9bc879f3e34e6..6498e41e2ecf9 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -731,7 +731,7 @@ static int unix_listen(struct socket *sock, int backlog) if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET) goto out; /* Only stream/seqpacket sockets accept */ err = -EINVAL; - if (!u->addr) + if (!READ_ONCE(u->addr)) goto out; /* No listens on an unbound socket */ unix_state_lock(sk); if (sk->sk_state != TCP_CLOSE && sk->sk_state != TCP_LISTEN) @@ -1369,7 +1369,7 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr, if ((test_bit(SOCK_PASSCRED, &sock->flags) || test_bit(SOCK_PASSPIDFD, &sock->flags)) && - !unix_sk(sk)->addr) { + !READ_ONCE(unix_sk(sk)->addr)) { err = unix_autobind(sk); if (err) goto out; @@ -1481,7 +1481,8 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr, goto out; if ((test_bit(SOCK_PASSCRED, &sock->flags) || - test_bit(SOCK_PASSPIDFD, &sock->flags)) && !u->addr) { + test_bit(SOCK_PASSPIDFD, &sock->flags)) && + !READ_ONCE(u->addr)) { err = unix_autobind(sk); if (err) goto out; @@ -1997,7 +1998,8 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg, } if ((test_bit(SOCK_PASSCRED, &sock->flags) || - test_bit(SOCK_PASSPIDFD, &sock->flags)) && !u->addr) { + test_bit(SOCK_PASSPIDFD, &sock->flags)) && + !READ_ONCE(u->addr)) { err = unix_autobind(sk); if (err) goto out; -- 2.43.0