From patchwork Fri Jul 19 14:32:20 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 11050211 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1C5A46C5 for ; Fri, 19 Jul 2019 14:32:46 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0B80D287C8 for ; Fri, 19 Jul 2019 14:32:46 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id F37EA28856; Fri, 19 Jul 2019 14:32:45 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 84604287C8 for ; Fri, 19 Jul 2019 14:32:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729867AbfGSOcl (ORCPT ); Fri, 19 Jul 2019 10:32:41 -0400 Received: from mx2.suse.de ([195.135.220.15]:41232 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729723AbfGSOc1 (ORCPT ); Fri, 19 Jul 2019 10:32:27 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 17B57B061; Fri, 19 Jul 2019 14:32:26 +0000 (UTC) From: Luis Henriques To: Ilya Dryomov , Jeff Layton , Sage Weil Cc: ceph-devel@vger.kernel.org, linux-kernel@vger.kernel.org, Luis Henriques Subject: [PATCH 2/4] ceph: fix buffer free while holding i_ceph_lock in __ceph_setxattr() Date: Fri, 19 Jul 2019 15:32:20 +0100 Message-Id: <20190719143222.16058-3-lhenriques@suse.com> In-Reply-To: <20190719143222.16058-1-lhenriques@suse.com> References: <20190719143222.16058-1-lhenriques@suse.com> MIME-Version: 1.0 Sender: ceph-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Calling ceph_buffer_put() in __ceph_setxattr() may end up freeing the i_xattrs.prealloc_blob buffer while holding the i_ceph_lock. This can be fixed by postponing the call until later, when the lock is released. The following backtrace was triggered by fstests generic/117. BUG: sleeping function called from invalid context at mm/vmalloc.c:2283 in_atomic(): 1, irqs_disabled(): 0, pid: 650, name: fsstress 3 locks held by fsstress/650: #0: 00000000870a0fe8 (sb_writers#8){.+.+}, at: mnt_want_write+0x20/0x50 #1: 00000000ba0c4c74 (&type->i_mutex_dir_key#6){++++}, at: vfs_setxattr+0x55/0xa0 #2: 000000008dfbb3f2 (&(&ci->i_ceph_lock)->rlock){+.+.}, at: __ceph_setxattr+0x297/0x810 CPU: 1 PID: 650 Comm: fsstress Not tainted 5.2.0+ #437 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack+0x67/0x90 ___might_sleep.cold+0x9f/0xb1 vfree+0x4b/0x60 ceph_buffer_release+0x1b/0x60 __ceph_setxattr+0x2b4/0x810 __vfs_setxattr+0x66/0x80 __vfs_setxattr_noperm+0x59/0xf0 vfs_setxattr+0x81/0xa0 setxattr+0x115/0x230 ? filename_lookup+0xc9/0x140 ? rcu_read_lock_sched_held+0x74/0x80 ? rcu_sync_lockdep_assert+0x2e/0x60 ? __sb_start_write+0x142/0x1a0 ? mnt_want_write+0x20/0x50 path_setxattr+0xba/0xd0 __x64_sys_lsetxattr+0x24/0x30 do_syscall_64+0x50/0x1c0 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7ff23514359a Signed-off-by: Luis Henriques --- fs/ceph/xattr.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c index 37b458a9af3a..c083557b3657 100644 --- a/fs/ceph/xattr.c +++ b/fs/ceph/xattr.c @@ -1036,6 +1036,7 @@ int __ceph_setxattr(struct inode *inode, const char *name, struct ceph_inode_info *ci = ceph_inode(inode); struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc; struct ceph_cap_flush *prealloc_cf = NULL; + struct ceph_buffer *old_blob = NULL; int issued; int err; int dirty = 0; @@ -1109,13 +1110,15 @@ int __ceph_setxattr(struct inode *inode, const char *name, struct ceph_buffer *blob; spin_unlock(&ci->i_ceph_lock); - dout(" preaallocating new blob size=%d\n", required_blob_size); + ceph_buffer_put(old_blob); /* Shouldn't be required */ + dout(" pre-allocating new blob size=%d\n", required_blob_size); blob = ceph_buffer_new(required_blob_size, GFP_NOFS); if (!blob) goto do_sync_unlocked; spin_lock(&ci->i_ceph_lock); + /* prealloc_blob can't be released while holding i_ceph_lock */ if (ci->i_xattrs.prealloc_blob) - ceph_buffer_put(ci->i_xattrs.prealloc_blob); + old_blob = ci->i_xattrs.prealloc_blob; ci->i_xattrs.prealloc_blob = blob; goto retry; } @@ -1131,6 +1134,7 @@ int __ceph_setxattr(struct inode *inode, const char *name, } spin_unlock(&ci->i_ceph_lock); + ceph_buffer_put(old_blob); if (lock_snap_rwsem) up_read(&mdsc->snap_rwsem); if (dirty)