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 AD1453B2FC1; Mon, 23 Mar 2026 14:42:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774276964; cv=none; b=tLBIkslwvT5t420S/aDiC4uo9xBdTPvk7bjvtVU8nUJGFi0R3x8Vau37gfz2V9scNdzyoX1VyHOBot4F1PjwtWhIU85KQ8fP6ZLdio+kJznXBVP3sf2kXEnxtJ+nbhXUe+14GvWdDs/rsOnpo9rPmFk07KV9FabfwW2/gy6i+hM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774276964; c=relaxed/simple; bh=TYIH2kLnNQSX3SQbEkLI6vgfzXFt2/K3/l2CDl24j5A=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iq/EC0XpHAGAW7xAdf88bJTMub+mrIHErLOrEVjeFSpRCs1jSW3okOWgFX/MUfdFveVLsP577AH4CMSGt1g1f6DHdrj7Te13TdKZQV/AfDLcXvWLukHp9NEeQORW6sFKpd8chsZC4Fbb9+TNz1FreXqRUdIq+6YTNb+aepj/XNE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=LC7i6z6f; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="LC7i6z6f" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 382DCC4CEF7; Mon, 23 Mar 2026 14:42:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774276964; bh=TYIH2kLnNQSX3SQbEkLI6vgfzXFt2/K3/l2CDl24j5A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LC7i6z6fYG24FtWnhwWF4N1v53hIqKbHtnFKwOZqIWb/a3L+uRD+E04P2dQx81eKB z6DdSPspXviQB/b8ZpPOabz9FcnF8SfrpVJ/ptCYWa4hufkO8PJ7wdHpcOCctyEzSf DWzb0GSz54mKY738dzliM8SsCT85EsdNE/p7iB2c= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Shyam Prasad N , Steve French , Sasha Levin Subject: [PATCH 6.12 270/460] cifs: open files should not hold ref on superblock Date: Mon, 23 Mar 2026 14:44:26 +0100 Message-ID: <20260323134533.121499571@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260323134526.647552166@linuxfoundation.org> References: <20260323134526.647552166@linuxfoundation.org> User-Agent: quilt/0.69 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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Shyam Prasad N [ Upstream commit 340cea84f691c5206561bb2e0147158fe02070be ] Today whenever we deal with a file, in addition to holding a reference on the dentry, we also get a reference on the superblock. This happens in two cases: 1. when a new cinode is allocated 2. when an oplock break is being processed The reasoning for holding the superblock ref was to make sure that when umount happens, if there are users of inodes and dentries, it does not try to clean them up and wait for the last ref to superblock to be dropped by last of such users. But the side effect of doing that is that umount silently drops a ref on the superblock and we could have deferred closes and lease breaks still holding these refs. Ideally, we should ensure that all of these users of inodes and dentries are cleaned up at the time of umount, which is what this code is doing. This code change allows these code paths to use a ref on the dentry (and hence the inode). That way, umount is ensured to clean up SMB client resources when it's the last ref on the superblock (For ex: when same objects are shared). The code change also moves the call to close all the files in deferred close list to the umount code path. It also waits for oplock_break workers to be flushed before calling kill_anon_super (which eventually frees up those objects). Fixes: 24261fc23db9 ("cifs: delay super block destruction until all cifsFileInfo objects are gone") Fixes: 705c79101ccf ("smb: client: fix use-after-free in cifs_oplock_break") Cc: Signed-off-by: Shyam Prasad N Signed-off-by: Steve French [ replaced kmalloc_obj() with kmalloc(sizeof(...)) ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/smb/client/cifsfs.c | 7 +++++-- fs/smb/client/cifsproto.h | 1 + fs/smb/client/file.c | 11 ----------- fs/smb/client/misc.c | 42 ++++++++++++++++++++++++++++++++++++++++++ fs/smb/client/trace.h | 2 ++ 5 files changed, 50 insertions(+), 13 deletions(-) --- a/fs/smb/client/cifsfs.c +++ b/fs/smb/client/cifsfs.c @@ -291,10 +291,14 @@ static void cifs_kill_sb(struct super_bl /* * We need to release all dentries for the cached directories - * before we kill the sb. + * and close all deferred file handles before we kill the sb. */ if (cifs_sb->root) { close_all_cached_dirs(cifs_sb); + cifs_close_all_deferred_files_sb(cifs_sb); + + /* Wait for all pending oplock breaks to complete */ + flush_workqueue(cifsoplockd_wq); /* finally release root dentry */ dput(cifs_sb->root); @@ -799,7 +803,6 @@ static void cifs_umount_begin(struct sup spin_unlock(&tcon->tc_lock); spin_unlock(&cifs_tcp_ses_lock); - cifs_close_all_deferred_files(tcon); /* cancel_brl_requests(tcon); */ /* BB mark all brl mids as exiting */ /* cancel_notify_requests(tcon); */ if (tcon->ses && tcon->ses->server) { --- a/fs/smb/client/cifsproto.h +++ b/fs/smb/client/cifsproto.h @@ -298,6 +298,7 @@ extern void cifs_close_deferred_file(str extern void cifs_close_all_deferred_files(struct cifs_tcon *cifs_tcon); +void cifs_close_all_deferred_files_sb(struct cifs_sb_info *cifs_sb); void cifs_close_deferred_file_under_dentry(struct cifs_tcon *cifs_tcon, struct dentry *dentry); --- a/fs/smb/client/file.c +++ b/fs/smb/client/file.c @@ -690,8 +690,6 @@ struct cifsFileInfo *cifs_new_fileinfo(s mutex_init(&cfile->fh_mutex); spin_lock_init(&cfile->file_info_lock); - cifs_sb_active(inode->i_sb); - /* * If the server returned a read oplock and we have mandatory brlocks, * set oplock level to None. @@ -746,7 +744,6 @@ static void cifsFileInfo_put_final(struc struct inode *inode = d_inode(cifs_file->dentry); struct cifsInodeInfo *cifsi = CIFS_I(inode); struct cifsLockInfo *li, *tmp; - struct super_block *sb = inode->i_sb; /* * Delete any outstanding lock records. We'll lose them when the file @@ -764,7 +761,6 @@ static void cifsFileInfo_put_final(struc cifs_put_tlink(cifs_file->tlink); dput(cifs_file->dentry); - cifs_sb_deactive(sb); kfree(cifs_file->symlink_target); kfree(cifs_file); } @@ -3075,12 +3071,6 @@ void cifs_oplock_break(struct work_struc __u64 persistent_fid, volatile_fid; __u16 net_fid; - /* - * Hold a reference to the superblock to prevent it and its inodes from - * being freed while we are accessing cinode. Otherwise, _cifsFileInfo_put() - * may release the last reference to the sb and trigger inode eviction. - */ - cifs_sb_active(sb); wait_on_bit(&cinode->flags, CIFS_INODE_PENDING_WRITERS, TASK_UNINTERRUPTIBLE); @@ -3153,7 +3143,6 @@ oplock_break_ack: cifs_put_tlink(tlink); out: cifs_done_oplock_break(cinode); - cifs_sb_deactive(sb); } static int cifs_swap_activate(struct swap_info_struct *sis, --- a/fs/smb/client/misc.c +++ b/fs/smb/client/misc.c @@ -27,6 +27,11 @@ #include "fs_context.h" #include "cached_dir.h" +struct tcon_list { + struct list_head entry; + struct cifs_tcon *tcon; +}; + /* The xid serves as a useful identifier for each incoming vfs request, in a similar way to the mid which is useful to track each sent smb, and CurrentXid can also provide a running counter (although it @@ -829,6 +834,43 @@ cifs_close_all_deferred_files(struct cif kfree(tmp_list); } } + +void cifs_close_all_deferred_files_sb(struct cifs_sb_info *cifs_sb) +{ + struct rb_root *root = &cifs_sb->tlink_tree; + struct rb_node *node; + struct cifs_tcon *tcon; + struct tcon_link *tlink; + struct tcon_list *tmp_list, *q; + LIST_HEAD(tcon_head); + + spin_lock(&cifs_sb->tlink_tree_lock); + for (node = rb_first(root); node; node = rb_next(node)) { + tlink = rb_entry(node, struct tcon_link, tl_rbnode); + tcon = tlink_tcon(tlink); + if (IS_ERR(tcon)) + continue; + tmp_list = kmalloc(sizeof(struct tcon_list), GFP_ATOMIC); + if (tmp_list == NULL) + break; + tmp_list->tcon = tcon; + /* Take a reference on tcon to prevent it from being freed */ + spin_lock(&tcon->tc_lock); + ++tcon->tc_count; + trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count, + netfs_trace_tcon_ref_get_close_defer_files); + spin_unlock(&tcon->tc_lock); + list_add_tail(&tmp_list->entry, &tcon_head); + } + spin_unlock(&cifs_sb->tlink_tree_lock); + + list_for_each_entry_safe(tmp_list, q, &tcon_head, entry) { + cifs_close_all_deferred_files(tmp_list->tcon); + list_del(&tmp_list->entry); + cifs_put_tcon(tmp_list->tcon, netfs_trace_tcon_ref_put_close_defer_files); + kfree(tmp_list); + } +} void cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon, struct dentry *dentry) --- a/fs/smb/client/trace.h +++ b/fs/smb/client/trace.h @@ -47,6 +47,7 @@ EM(netfs_trace_tcon_ref_get_cached_laundromat, "GET Ch-Lau") \ EM(netfs_trace_tcon_ref_get_cached_lease_break, "GET Ch-Lea") \ EM(netfs_trace_tcon_ref_get_cancelled_close, "GET Cn-Cls") \ + EM(netfs_trace_tcon_ref_get_close_defer_files, "GET Cl-Def") \ EM(netfs_trace_tcon_ref_get_dfs_refer, "GET DfsRef") \ EM(netfs_trace_tcon_ref_get_find, "GET Find ") \ EM(netfs_trace_tcon_ref_get_find_sess_tcon, "GET FndSes") \ @@ -58,6 +59,7 @@ EM(netfs_trace_tcon_ref_put_cancelled_close, "PUT Cn-Cls") \ EM(netfs_trace_tcon_ref_put_cancelled_close_fid, "PUT Cn-Fid") \ EM(netfs_trace_tcon_ref_put_cancelled_mid, "PUT Cn-Mid") \ + EM(netfs_trace_tcon_ref_put_close_defer_files, "PUT Cl-Def") \ EM(netfs_trace_tcon_ref_put_mnt_ctx, "PUT MntCtx") \ EM(netfs_trace_tcon_ref_put_dfs_refer, "PUT DfsRfr") \ EM(netfs_trace_tcon_ref_put_reconnect_server, "PUT Reconn") \