From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 18B98C3A5A6 for ; Thu, 29 Aug 2019 21:16:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DCAA62189D for ; Thu, 29 Aug 2019 21:16:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567113403; bh=S8jZl5qXwtASsh5sqmmpoIddnxCBuXvV58tUABgzZKo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=2X0DWI78v7j3jStpdyt3U+c96p8W0m1bLU6fsgHcPqcKYPBkOSqiAHJ5sSvcUHg+5 Pi/RGanKBRNzGdFvZOkSHJLXn4zTQLLwo0AyIU8TpTKwyohAuH/eHf3FClVp1nC7V5 ywt6j5Y0/qbvz6q+vz7QGq+lIRN20foPD6/k2BDk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728003AbfH2VQn (ORCPT ); Thu, 29 Aug 2019 17:16:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:55106 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726526AbfH2VQm (ORCPT ); Thu, 29 Aug 2019 17:16:42 -0400 Received: from localhost (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3CECB208C2; Thu, 29 Aug 2019 21:16:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567113401; bh=S8jZl5qXwtASsh5sqmmpoIddnxCBuXvV58tUABgzZKo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pf4R/qE5U0ptoMvA6pBMA2mE1A59uGzHclP0IcO1McDCsMmRqgD/adkoEj+nu59xk dR/inm3HdrOS6Hml8x/aWb6cykxATePFa/h5RbsRBepApDwGyxBIOKpa6ihPstjoLd QEcnRqw1Vl2tvAuVCKYZI6mtQlXlE9yeSISENWnw= Date: Thu, 29 Aug 2019 17:16:40 -0400 From: Sasha Levin To: Ilya Dryomov Cc: LKML , stable@vger.kernel.org, Luis Henriques , Jeff Layton , Ceph Development Subject: Re: [PATCH AUTOSEL 5.2 66/76] ceph: fix buffer free while holding i_ceph_lock in __ceph_setxattr() Message-ID: <20190829211640.GN5281@sasha-vm> References: <20190829181311.7562-1-sashal@kernel.org> <20190829181311.7562-66-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 29, 2019 at 10:51:04PM +0200, Ilya Dryomov wrote: >On Thu, Aug 29, 2019 at 8:15 PM Sasha Levin wrote: >> >> From: Luis Henriques >> >> [ Upstream commit 86968ef21596515958d5f0a40233d02be78ecec0 ] >> >> 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 >> Reviewed-by: Jeff Layton >> Signed-off-by: Ilya Dryomov >> Signed-off-by: Sasha Levin >> --- >> 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 0619adbcbe14c..8382299fc2d84 100644 >> --- a/fs/ceph/xattr.c >> +++ b/fs/ceph/xattr.c >> @@ -1028,6 +1028,7 @@ 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; >> @@ -1101,13 +1102,15 @@ 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; >> } >> @@ -1123,6 +1126,7 @@ 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) > >Hi Sasha, > >I didn't tag i_ceph_lock series for stable because this is a very old >bug which no one ever hit in real life, at least to my knowledge. I can drop it if you prefer. -- Thanks, Sasha