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 E402E1BDEC; Wed, 3 Jan 2024 16:59:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="TCtBlHzC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 346B0C433C7; Wed, 3 Jan 2024 16:59:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1704301163; bh=XKWW1mA68MiITNszjVgpMhbG89QxduenAawTDP/wRPk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TCtBlHzCqvbqhE1guLlGGx09RIRKjUxjgK+OSWQYUuDA51y/ltJmWfzmyKMHMmMEz EqteJ/N3iMBZRTsEju+ZwvjFX81upYP5h3teQHGkvL/R8ALzNCTYYWtQWLHorhr+E2 MqJl3e6Mn43L6llljGh9yNLBkrwwC5L/m6XzEhEQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Marios Makassikis , Namjae Jeon , Steve French , Sasha Levin Subject: [PATCH 6.1 055/100] ksmbd: fix recursive locking in vfs helpers Date: Wed, 3 Jan 2024 17:54:44 +0100 Message-ID: <20240103164904.339806348@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240103164856.169912722@linuxfoundation.org> References: <20240103164856.169912722@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Marios Makassikis [ Upstream commit 807252f028c59b9a3bac4d62ad84761548c10f11 ] Running smb2.rename test from Samba smbtorture suite against a kernel built with lockdep triggers a "possible recursive locking detected" warning. This is because mnt_want_write() is called twice with no mnt_drop_write() in between: -> ksmbd_vfs_mkdir() -> ksmbd_vfs_kern_path_create() -> kern_path_create() -> filename_create() -> mnt_want_write() -> mnt_want_write() Fix this by removing the mnt_want_write/mnt_drop_write calls from vfs helpers that call kern_path_create(). Full lockdep trace below: ============================================ WARNING: possible recursive locking detected 6.6.0-rc5 #775 Not tainted -------------------------------------------- kworker/1:1/32 is trying to acquire lock: ffff888005ac83f8 (sb_writers#5){.+.+}-{0:0}, at: ksmbd_vfs_mkdir+0xe1/0x410 but task is already holding lock: ffff888005ac83f8 (sb_writers#5){.+.+}-{0:0}, at: filename_create+0xb6/0x260 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(sb_writers#5); lock(sb_writers#5); *** DEADLOCK *** May be due to missing lock nesting notation 4 locks held by kworker/1:1/32: #0: ffff8880064e4138 ((wq_completion)ksmbd-io){+.+.}-{0:0}, at: process_one_work+0x40e/0x980 #1: ffff888005b0fdd0 ((work_completion)(&work->work)){+.+.}-{0:0}, at: process_one_work+0x40e/0x980 #2: ffff888005ac83f8 (sb_writers#5){.+.+}-{0:0}, at: filename_create+0xb6/0x260 #3: ffff8880057ce760 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: filename_create+0x123/0x260 Cc: stable@vger.kernel.org Fixes: 40b268d384a2 ("ksmbd: add mnt_want_write to ksmbd vfs functions") Signed-off-by: Marios Makassikis Acked-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Sasha Levin --- fs/smb/server/vfs.c | 23 +++-------------------- 1 file changed, 3 insertions(+), 20 deletions(-) diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c index 071c344dd0333..e2e454eba4095 100644 --- a/fs/smb/server/vfs.c +++ b/fs/smb/server/vfs.c @@ -174,10 +174,6 @@ int ksmbd_vfs_create(struct ksmbd_work *work, const char *name, umode_t mode) return err; } - err = mnt_want_write(path.mnt); - if (err) - goto out_err; - mode |= S_IFREG; err = vfs_create(mnt_user_ns(path.mnt), d_inode(path.dentry), dentry, mode, true); @@ -187,9 +183,7 @@ int ksmbd_vfs_create(struct ksmbd_work *work, const char *name, umode_t mode) } else { pr_err("File(%s): creation failed (err:%d)\n", name, err); } - mnt_drop_write(path.mnt); -out_err: done_path_create(&path, dentry); return err; } @@ -220,10 +214,6 @@ int ksmbd_vfs_mkdir(struct ksmbd_work *work, const char *name, umode_t mode) return err; } - err = mnt_want_write(path.mnt); - if (err) - goto out_err2; - user_ns = mnt_user_ns(path.mnt); mode |= S_IFDIR; err = vfs_mkdir(user_ns, d_inode(path.dentry), dentry, mode); @@ -234,21 +224,19 @@ int ksmbd_vfs_mkdir(struct ksmbd_work *work, const char *name, umode_t mode) dentry->d_name.len); if (IS_ERR(d)) { err = PTR_ERR(d); - goto out_err1; + goto out_err; } if (unlikely(d_is_negative(d))) { dput(d); err = -ENOENT; - goto out_err1; + goto out_err; } ksmbd_vfs_inherit_owner(work, d_inode(path.dentry), d_inode(d)); dput(d); } -out_err1: - mnt_drop_write(path.mnt); -out_err2: +out_err: done_path_create(&path, dentry); if (err) pr_err("mkdir(%s): creation failed (err:%d)\n", name, err); @@ -666,16 +654,11 @@ int ksmbd_vfs_link(struct ksmbd_work *work, const char *oldname, goto out3; } - err = mnt_want_write(newpath.mnt); - if (err) - goto out3; - err = vfs_link(oldpath.dentry, mnt_user_ns(newpath.mnt), d_inode(newpath.dentry), dentry, NULL); if (err) ksmbd_debug(VFS, "vfs_link failed err %d\n", err); - mnt_drop_write(newpath.mnt); out3: done_path_create(&newpath, dentry); -- 2.43.0