The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
Possible dependencies:
7f28af9cf542 ("cifs: fix potential use-after-free bugs")
0e62904836ec ("smb3: remove trivial dfs compile warning")
c88f7dcd6d64 ("cifs: support nested dfs links over reconnect")
bbcce3680445 ("cifs: split out dfs code from cifs_reconnect()")
43b459aa5e22 ("cifs: introduce new helper for cifs_reconnect()")
7be3248f3139 ("cifs: To match file servers, make sure the server hostname matches")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 7f28af9cf542f61758b982f8304f951ca99c8f58 Mon Sep 17 00:00:00 2001
From: Paulo Alcantara <pc@xxxxxx>
Date: Fri, 12 Nov 2021 15:16:08 -0300
Subject: [PATCH] cifs: fix potential use-after-free bugs
Ensure that share and prefix variables are set to NULL after kfree()
when looping through DFS targets in __tree_connect_dfs_target().
Also, get rid of @ref in __tree_connect_dfs_target() and just pass a
boolean to indicate whether we're handling link targets or not.
Fixes: c88f7dcd6d64 ("cifs: support nested dfs links over reconnect")
Signed-off-by: Paulo Alcantara (SUSE) <pc@xxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index ae21dff02f30..5c506f6ecd65 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -4141,14 +4141,13 @@ static int target_share_matches_server(struct TCP_Server_Info *server, const cha
}
static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *tcon,
- struct cifs_sb_info *cifs_sb, char *tree,
- struct dfs_cache_tgt_list *tl, struct dfs_info3_param *ref)
+ struct cifs_sb_info *cifs_sb, char *tree, bool islink,
+ struct dfs_cache_tgt_list *tl)
{
int rc;
struct TCP_Server_Info *server = tcon->ses->server;
const struct smb_version_operations *ops = server->ops;
struct cifs_tcon *ipc = tcon->ses->tcon_ipc;
- bool islink;
char *share = NULL, *prefix = NULL;
const char *tcp_host;
size_t tcp_host_len;
@@ -4157,9 +4156,6 @@ static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *t
extract_unc_hostname(server->hostname, &tcp_host, &tcp_host_len);
- islink = ref->server_type == DFS_TYPE_LINK;
- free_dfs_info_param(ref);
-
tit = dfs_cache_get_tgt_iterator(tl);
if (!tit) {
rc = -ENOENT;
@@ -4173,6 +4169,7 @@ static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *t
kfree(share);
kfree(prefix);
+ share = prefix = NULL;
/* Check if share matches with tcp ses */
rc = dfs_cache_get_tgt_share(server->current_fullpath + 1, tit, &share, &prefix);
@@ -4209,25 +4206,23 @@ static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *t
* newly resolved target.
*/
if (dfs_cache_find(xid, tcon->ses, cifs_sb->local_nls, cifs_remap(cifs_sb), target,
- ref, &ntl)) {
+ NULL, &ntl)) {
rc = ops->tree_connect(xid, tcon->ses, tree, tcon, cifs_sb->local_nls);
if (rc)
continue;
rc = dfs_cache_noreq_update_tgthint(server->current_fullpath + 1, tit);
if (!rc)
rc = cifs_update_super_prepath(cifs_sb, prefix);
- break;
- }
- /* Target is another dfs share */
- rc = update_server_fullpath(server, cifs_sb, target);
- dfs_cache_free_tgts(tl);
-
- if (!rc) {
- rc = -EREMOTE;
- list_replace_init(&ntl.tl_list, &tl->tl_list);
} else {
- dfs_cache_free_tgts(&ntl);
- free_dfs_info_param(ref);
+ /* Target is another dfs share */
+ rc = update_server_fullpath(server, cifs_sb, target);
+ dfs_cache_free_tgts(tl);
+
+ if (!rc) {
+ rc = -EREMOTE;
+ list_replace_init(&ntl.tl_list, &tl->tl_list);
+ } else
+ dfs_cache_free_tgts(&ntl);
}
break;
}
@@ -4240,15 +4235,15 @@ static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *t
}
static int tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *tcon,
- struct cifs_sb_info *cifs_sb, char *tree,
- struct dfs_cache_tgt_list *tl, struct dfs_info3_param *ref)
+ struct cifs_sb_info *cifs_sb, char *tree, bool islink,
+ struct dfs_cache_tgt_list *tl)
{
int rc;
int num_links = 0;
struct TCP_Server_Info *server = tcon->ses->server;
do {
- rc = __tree_connect_dfs_target(xid, tcon, cifs_sb, tree, tl, ref);
+ rc = __tree_connect_dfs_target(xid, tcon, cifs_sb, tree, islink, tl);
if (!rc || rc != -EREMOTE)
break;
} while (rc = -ELOOP, ++num_links < MAX_NESTED_LINKS);
@@ -4302,7 +4297,9 @@ int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const stru
goto out;
}
- rc = tree_connect_dfs_target(xid, tcon, cifs_sb, tree, &tl, &ref);
+ rc = tree_connect_dfs_target(xid, tcon, cifs_sb, tree, ref.server_type == DFS_TYPE_LINK,
+ &tl);
+ free_dfs_info_param(&ref);
out:
kfree(tree);
