cifs: NULL out tcon, pSesInfo, and srvTcp pointers when chasing DFS referrals

The scenario is this:

The kernel gets EREMOTE and starts chasing a DFS referral at mount time.
The tcon reference is put, which puts the session reference too, but
neither pointer is zeroed out.

The mount gets retried (goto try_mount_again) with new mount info.
Session setup fails fails and rc ends up being non-zero. The code then
falls through to the end and tries to put the previously freed tcon
pointer again.  Oops at: cifs_put_smb_ses+0x14/0xd0

Fix this by moving the initialization of the rc variable and the tcon,
pSesInfo and srvTcp pointers below the try_mount_again label. Also, add
a FreeXid() before the goto to prevent xid "leaks".

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reported-by: Gustavo Carvalho Homem <gustavo@angulosolido.pt>
CC: stable <stable@kernel.org>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 63ea83ff687f..3bbcaa716b3c 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2287,12 +2287,12 @@ int
 cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
                 char *mount_data_global, const char *devname)
 {
-        int rc = 0;
+        int rc;
         int xid;
         struct smb_vol *volume_info;
-        struct cifsSesInfo *pSesInfo = NULL;
-        struct cifsTconInfo *tcon = NULL;
-        struct TCP_Server_Info *srvTcp = NULL;
+        struct cifsSesInfo *pSesInfo;
+        struct cifsTconInfo *tcon;
+        struct TCP_Server_Info *srvTcp;
         char   *full_path;
         char *mount_data = mount_data_global;
 #ifdef CONFIG_CIFS_DFS_UPCALL
@@ -2301,6 +2301,10 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
         int referral_walks_count = 0;
 try_mount_again:
 #endif
+        rc = 0;
+        tcon = NULL;
+        pSesInfo = NULL;
+        srvTcp = NULL;
         full_path = NULL;
 
         xid = GetXid();
@@ -2597,6 +2601,7 @@ remote_path_check:
 
                         cleanup_volume_info(&volume_info);
                         referral_walks_count++;
+                        FreeXid(xid);
                         goto try_mount_again;
                 }
 #else /* No DFS support, return error on mount */