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 9426828DC3; Fri, 24 Nov 2023 18:37:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="HsMlOSOM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1C81FC433C8; Fri, 24 Nov 2023 18:37:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1700851078; bh=9vdQmh6O/mUDrLwtzMpTesqCzKfM6ooym4OrNGeTQ1c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HsMlOSOMASjLOru7ddipybCV5JNTt4lmHOYrCczRheGAH7KGs1U/CEGiV61QjcAch KO2cTKEZzll60zFYrrO1hAncGbKVKXEf5rwvBfZQf3CdqgbzNZUgehF9NpePue7rKP NJpU5tojD+Dr6maQ5fu26VaRLJPvDhaMFoWLrFCY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Marios Makassikis , Namjae Jeon , Steve French Subject: [PATCH 6.5 297/491] ksmbd: fix recursive locking in vfs helpers Date: Fri, 24 Nov 2023 17:48:53 +0000 Message-ID: <20231124172033.500445185@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231124172024.664207345@linuxfoundation.org> References: <20231124172024.664207345@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 6.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Marios Makassikis commit 807252f028c59b9a3bac4d62ad84761548c10f11 upstream. 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: Greg Kroah-Hartman --- fs/smb/server/vfs.c | 23 +++-------------------- 1 file changed, 3 insertions(+), 20 deletions(-) --- a/fs/smb/server/vfs.c +++ b/fs/smb/server/vfs.c @@ -173,10 +173,6 @@ int ksmbd_vfs_create(struct ksmbd_work * return err; } - err = mnt_want_write(path.mnt); - if (err) - goto out_err; - mode |= S_IFREG; err = vfs_create(mnt_idmap(path.mnt), d_inode(path.dentry), dentry, mode, true); @@ -186,9 +182,7 @@ int ksmbd_vfs_create(struct ksmbd_work * } 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; } @@ -219,10 +213,6 @@ int ksmbd_vfs_mkdir(struct ksmbd_work *w return err; } - err = mnt_want_write(path.mnt); - if (err) - goto out_err2; - idmap = mnt_idmap(path.mnt); mode |= S_IFDIR; err = vfs_mkdir(idmap, d_inode(path.dentry), dentry, mode); @@ -233,21 +223,19 @@ int ksmbd_vfs_mkdir(struct ksmbd_work *w 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); @@ -665,16 +653,11 @@ int ksmbd_vfs_link(struct ksmbd_work *wo goto out3; } - err = mnt_want_write(newpath.mnt); - if (err) - goto out3; - err = vfs_link(oldpath.dentry, mnt_idmap(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);