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=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 BF069C3A5A6 for ; Fri, 30 Aug 2019 08:28:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9331A21874 for ; Fri, 30 Aug 2019 08:28:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="J0175i7P" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728129AbfH3I2v (ORCPT ); Fri, 30 Aug 2019 04:28:51 -0400 Received: from mail-io1-f68.google.com ([209.85.166.68]:43417 "EHLO mail-io1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726480AbfH3I2v (ORCPT ); Fri, 30 Aug 2019 04:28:51 -0400 Received: by mail-io1-f68.google.com with SMTP id u185so8581361iod.10; Fri, 30 Aug 2019 01:28:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=FnQGezDYO5hoi4qMr6hFteu6J0hxc2afK6Bu1JCgpJs=; b=J0175i7PLeHrpTIwJsAcjfdidXf+v04TTsZELE9ltkPQ4tU0FTMGiEGfrh7gzahRcN gI+2m7WmnEzGmVtL3lyOvPLu7WpeJgT7zFZPDvYyusZZXIYHpGS3KoTemenCmRAWNvKQ lBpSeCe5b/5846aDMypZHsV6xObfkqZ8XP2ezfzf/I4kGiRPvHd4/D2+X+aU5u9bFwzI DiL9qH19yqf1m3gkHvPWFC5Ra2kJjO2qSOMNd4qfNlma5nCIVbpbA2RF+V1MnAC8nV4E uKvZ0eEVqRYb8OGAV3fCBPv+5v/DwhFuh55ASVp/AvZmnT2aKq0ZeEE+qRi4aVlcJo9Z 7XTw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=FnQGezDYO5hoi4qMr6hFteu6J0hxc2afK6Bu1JCgpJs=; b=nsDDoj16Ko9L5+cmuHbARIBt1qVToQ8rrPEtJf23Zn2X45QIFnB6NuXYVsribmrO4I sHVGn1mwN9yBds6FChZp2hprEF2emEHIBfmqdHLZWPbAEHKAWIbHRLZh9FiRXiaqppWl gx0AJwS0MQGkwHwtBnAJZCllfny4qrUV92C510HBwJu474kPBoYjt0RcvbTrjpCJI/9c WYR4arC57MVTx7eQaxyfSdFxcRRKUEJQ3UmQAFDv1k8M+5m53CJXjj73Q7L1leL5TS6H a7e7zntT2FXRRY0pdj547NNOl5qGgwMp5RNkDnVKfTHxX1WrkmqN5MWWoc1tckD3D1wd 8tDA== X-Gm-Message-State: APjAAAX6A9dBjj/J37LJaewwBS+0XiZuREmb1sBaLG1Ha0BuvmvnE1sr zztxQm9lGDqp3C75uzjhLTdJCb1c6e0pSvvrpRU= X-Google-Smtp-Source: APXvYqzh4ZWbYUgOrIXRKzNwKFlVdvLdRsMAd4czJUiBBQ34pQ8gvCsfatlbWy3/zbYJpGODP3+G603e8CbSc4iZKHc= X-Received: by 2002:a5d:9d49:: with SMTP id k9mr1449448iok.106.1567153729688; Fri, 30 Aug 2019 01:28:49 -0700 (PDT) MIME-Version: 1.0 References: <20190829181311.7562-1-sashal@kernel.org> <20190829181311.7562-66-sashal@kernel.org> <20190829211640.GN5281@sasha-vm> In-Reply-To: <20190829211640.GN5281@sasha-vm> From: Ilya Dryomov Date: Fri, 30 Aug 2019 10:31:53 +0200 Message-ID: Subject: Re: [PATCH AUTOSEL 5.2 66/76] ceph: fix buffer free while holding i_ceph_lock in __ceph_setxattr() To: Sasha Levin Cc: LKML , stable@vger.kernel.org, Luis Henriques , Jeff Layton , Ceph Development Content-Type: text/plain; charset="UTF-8" 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 11:16 PM Sasha Levin wrote: > > 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. Either is fine with me. I just wanted to explain my rationale for not tagging them for stable in the first place and point out that there is a prerequisite. Thanks, Ilya