From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-1825685-1518708232-3-4259143134857517313 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.001, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1518708231; b=rKUqrQDo4wmA/x93zMx7+MIR2IUqE+1FIcCDzoXcmNVniUv eoTTz85wBnWpdbJF0sMaIKS9tQgUoqY+5hVkHUuJsC0MlBJZfwIqTbH/b7geaW6y VHDVQIkj/2TkAaqT5Ku90q5ZpLK7igYgdd9nDh01NMcIcktBORCYtjhyW4jDqRfi kL3whY1pnJcMyb1dZ/yVoDsRaT4Rx/TRoJfuiutTHLuulmcUnMjBf/Jr5dPmIXAo wn5qtjWwmrRRWwOlZgMzicAgtoyNG29v29tQAtPOW5+2TkeGKT1NQlM14ZXPKhYG kdyuOzbxayVZlPCZ2j5eOhwAbQIF5LwK+ohFU+w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-type:sender :list-id; s=arctest; t=1518708231; bh=Ce65ZQ7KSD9iENQh1X5DYM4YKt 5Pd+NNYUCxAR5ePxk=; b=CX77Yrf4bDdYRosPC1SarumNGDEzUKKDdA8HxUpa+Y v0oNWIKQB7ow/N4m/FoPakU8POETLZvvBKHfiyazBAThhhysJBxwYm/nT/+CwiAQ M9WO+NrI2266lapf7OX9M0Q8Nvr1hEFd/6GJLzdh25Pj5Om1/BYlTeSOlOgZ8mvv sQbmeLBLXc75y6JN6yCJwWZ9I40mmgyFiftGOLHkn9mFXjkxmZNfTuGyPo3IMYqP zJ+T5vCe9ZQKpUyKOoutDbzwhYvMTa1Yi0qJ9MEaWBfA3lQX1eJnaMyRkoVrRY6I NJm6bdRCeZDtbjrHtkGE9KJ05s4xr4E8ufo9TNwHrcqQ== ARC-Authentication-Results: i=1; mx4.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Authentication-Results: mx4.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1162750AbeBOPXs (ORCPT ); Thu, 15 Feb 2018 10:23:48 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:51584 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1162739AbeBOPXr (ORCPT ); Thu, 15 Feb 2018 10:23:47 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexander Viro , Andrew Morton , Andrey Konovalov , Cong Wang , Linus Torvalds , Eric Biggers Subject: [PATCH 4.4 070/108] nsfs: mark dentry with DCACHE_RCUACCESS Date: Thu, 15 Feb 2018 16:17:07 +0100 Message-Id: <20180215151232.115260005@linuxfoundation.org> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180215151222.267507937@linuxfoundation.org> References: <20180215151222.267507937@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Cong Wang commit 073c516ff73557a8f7315066856c04b50383ac34 upstream. Andrey reported a use-after-free in __ns_get_path(): spin_lock include/linux/spinlock.h:299 [inline] lockref_get_not_dead+0x19/0x80 lib/lockref.c:179 __ns_get_path+0x197/0x860 fs/nsfs.c:66 open_related_ns+0xda/0x200 fs/nsfs.c:143 sock_ioctl+0x39d/0x440 net/socket.c:1001 vfs_ioctl fs/ioctl.c:45 [inline] do_vfs_ioctl+0x1bf/0x1780 fs/ioctl.c:685 SYSC_ioctl fs/ioctl.c:700 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691 We are under rcu read lock protection at that point: rcu_read_lock(); d = atomic_long_read(&ns->stashed); if (!d) goto slow; dentry = (struct dentry *)d; if (!lockref_get_not_dead(&dentry->d_lockref)) goto slow; rcu_read_unlock(); but don't use a proper RCU API on the free path, therefore a parallel __d_free() could free it at the same time. We need to mark the stashed dentry with DCACHE_RCUACCESS so that __d_free() will be called after all readers leave RCU. Fixes: e149ed2b805f ("take the targets of /proc/*/ns/* symlinks to separate fs") Cc: Alexander Viro Cc: Andrew Morton Reported-by: Andrey Konovalov Signed-off-by: Cong Wang Signed-off-by: Linus Torvalds Cc: Eric Biggers Signed-off-by: Greg Kroah-Hartman --- fs/nsfs.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/nsfs.c +++ b/fs/nsfs.c @@ -95,6 +95,7 @@ slow: return ERR_PTR(-ENOMEM); } d_instantiate(dentry, inode); + dentry->d_flags |= DCACHE_RCUACCESS; dentry->d_fsdata = (void *)ns_ops; d = atomic_long_cmpxchg(&ns->stashed, 0, (unsigned long)dentry); if (d) {