This is a note to let you know that I've just added the patch titled
cifs: fix potential race when tree connecting ipc
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cifs-fix-potential-race-when-tree-connecting-ipc.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ee20d7c6100752eaf2409d783f4f1449c29ea33d Mon Sep 17 00:00:00 2001
From: Paulo Alcantara <pc@xxxxxxxxxxxxx>
Date: Tue, 25 Apr 2023 02:42:56 -0300
Subject: cifs: fix potential race when tree connecting ipc
From: Paulo Alcantara <pc@xxxxxxxxxxxxx>
commit ee20d7c6100752eaf2409d783f4f1449c29ea33d upstream.
Protect access of TCP_Server_Info::hostname when building the ipc tree
name as it might get freed in cifsd thread and thus causing an
use-after-free bug in __tree_connect_dfs_target(). Also, while at it,
update status of IPC tcon on success and then avoid any extra tree
connects.
Cc: stable@xxxxxxxxxxxxxxx # v6.2+
Signed-off-by: Paulo Alcantara (SUSE) <pc@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/cifs/dfs.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 50 insertions(+), 7 deletions(-)
--- a/fs/cifs/dfs.c
+++ b/fs/cifs/dfs.c
@@ -398,6 +398,54 @@ static int target_share_matches_server(s
return rc;
}
+static void __tree_connect_ipc(const unsigned int xid, char *tree,
+ struct cifs_sb_info *cifs_sb,
+ struct cifs_ses *ses)
+{
+ struct TCP_Server_Info *server = ses->server;
+ struct cifs_tcon *tcon = ses->tcon_ipc;
+ int rc;
+
+ spin_lock(&ses->ses_lock);
+ spin_lock(&ses->chan_lock);
+ if (cifs_chan_needs_reconnect(ses, server) ||
+ ses->ses_status != SES_GOOD) {
+ spin_unlock(&ses->chan_lock);
+ spin_unlock(&ses->ses_lock);
+ cifs_server_dbg(FYI, "%s: skipping ipc reconnect due to disconnected ses\n",
+ __func__);
+ return;
+ }
+ spin_unlock(&ses->chan_lock);
+ spin_unlock(&ses->ses_lock);
+
+ cifs_server_lock(server);
+ scnprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$", server->hostname);
+ cifs_server_unlock(server);
+
+ rc = server->ops->tree_connect(xid, ses, tree, tcon,
+ cifs_sb->local_nls);
+ cifs_server_dbg(FYI, "%s: tree_reconnect %s: %d\n", __func__, tree, rc);
+ spin_lock(&tcon->tc_lock);
+ if (rc) {
+ tcon->status = TID_NEED_TCON;
+ } else {
+ tcon->status = TID_GOOD;
+ tcon->need_reconnect = false;
+ }
+ spin_unlock(&tcon->tc_lock);
+}
+
+static void tree_connect_ipc(const unsigned int xid, char *tree,
+ struct cifs_sb_info *cifs_sb,
+ struct cifs_tcon *tcon)
+{
+ struct cifs_ses *ses = tcon->ses;
+
+ __tree_connect_ipc(xid, tree, cifs_sb, ses);
+ __tree_connect_ipc(xid, tree, cifs_sb, CIFS_DFS_ROOT_SES(ses));
+}
+
static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *tcon,
struct cifs_sb_info *cifs_sb, char *tree, bool islink,
struct dfs_cache_tgt_list *tl)
@@ -406,7 +454,6 @@ static int __tree_connect_dfs_target(con
struct TCP_Server_Info *server = tcon->ses->server;
const struct smb_version_operations *ops = server->ops;
struct cifs_ses *root_ses = CIFS_DFS_ROOT_SES(tcon->ses);
- struct cifs_tcon *ipc = root_ses->tcon_ipc;
char *share = NULL, *prefix = NULL;
struct dfs_cache_tgt_iterator *tit;
bool target_match;
@@ -442,18 +489,14 @@ static int __tree_connect_dfs_target(con
}
dfs_cache_noreq_update_tgthint(server->current_fullpath + 1, tit);
-
- if (ipc->need_reconnect) {
- scnprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$", server->hostname);
- rc = ops->tree_connect(xid, ipc->ses, tree, ipc, cifs_sb->local_nls);
- cifs_dbg(FYI, "%s: reconnect ipc: %d\n", __func__, rc);
- }
+ tree_connect_ipc(xid, tree, cifs_sb, tcon);
scnprintf(tree, MAX_TREE_SIZE, "\\%s", share);
if (!islink) {
rc = ops->tree_connect(xid, tcon->ses, tree, tcon, cifs_sb->local_nls);
break;
}
+
/*
* If no dfs referrals were returned from link target, then just do a TREE_CONNECT
* to it. Otherwise, cache the dfs referral and then mark current tcp ses for
Patches currently in stable-queue which might be from pc@xxxxxxxxxxxxx are
queue-6.2/cifs-protect-access-of-tcp_server_info-origin-leaf-_fullpath.patch
queue-6.2/cifs-fix-sharing-of-dfs-connections.patch
queue-6.2/cifs-fix-potential-use-after-free-bugs-in-tcp_server_info-hostname.patch
queue-6.2/smb3-add-missing-locks-to-protect-deferred-close-fil.patch
queue-6.2/cifs-fix-potential-race-when-tree-connecting-ipc.patch
queue-6.2/cifs-protect-session-status-check-in-smb2_reconnect.patch
