smb: client: fix potential UAF in cifs_debug_files_proc_show()

commit ca545b7f0823f19db0f1148d59bc5e1a56634502 upstream.

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

Cc: stable@vger.kernel.org
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/smb/client/cifs_debug.c b/fs/smb/client/cifs_debug.c
index 7206167f4184a92026db828458b6f0e0e67e673e..82cac81696021cab3b2cbe641bd357ce8d0b43dd 100644 (file)
--- 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 b99767c8d37313bac172a01af087013b87c34b36..a878b1e5aa313a2ea35811652822baca6112c8b5 100644 (file)
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -2281,4 +2281,14 @@ struct smb2_compound_vars {
        struct smb2_file_link_info link_info;
 };
 
+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 */