From: Paulo Alcantara pc@manguebit.com
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@vger.kernel.org # v6.2+ Signed-off-by: Paulo Alcantara (SUSE) pc@manguebit.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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