[PATCH 01/12] smb: client: fix potential UAF in cifs_debug_files_proc_show()

[Paulo Alcantara <pc@manguebit.com>]

Skip sessions that are being teared down (status == SES_EXITING) to
avoid UAF.

Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
---
 fs/smb/client/cifs_debug.c |  2 ++
 fs/smb/client/cifsglob.h   | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/fs/smb/client/cifs_debug.c b/fs/smb/client/cifs_debug.c
index 226d4835c92d..c9aec9a38ad3 100644
--- a/fs/smb/client/cifs_debug.c
+++ b/fs/smb/client/cifs_debug.c
@@ -250,6 +250,8 @@ static int cifs_debug_files_proc_show(struct seq_file *m, void *v)
 	spin_lock(&cifs_tcp_ses_lock);
 	list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
 		list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
+			if (cifs_ses_exiting(ses))
+				continue;
 			list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
 				spin_lock(&tcon->open_file_lock);
 				list_for_each_entry(cfile, &tcon->openFileList, tlist) {
diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index 286afbe346be..f67607319c43 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -2322,4 +2322,14 @@ struct smb2_compound_vars {
 	struct kvec ea_iov;
 };
 
+static inline bool cifs_ses_exiting(struct cifs_ses *ses)
+{
+	bool ret;
+
+	spin_lock(&ses->ses_lock);
+	ret = ses->ses_status == SES_EXITING;
+	spin_unlock(&ses->ses_lock);
+	return ret;
+}
+
 #endif	/* _CIFS_GLOB_H */
-- 
2.44.0