Fix refcount underflow warning when unmounting to servers which didn't grant
directory leases.
[ 301.680095] refcount_t: underflow; use-after-free.
[ 301.680192] WARNING: CPU: 1 PID: 3569 at lib/refcount.c:28
refcount_warn_saturate+0xb4/0xf3
...
[ 301.682139] Call Trace:
[ 301.682240] close_shroot+0x97/0xda [cifs]
[ 301.682351] SMB2_tdis+0x7c/0x176 [cifs]
[ 301.682456] ? _get_xid+0x58/0x91 [cifs]
[ 301.682563] cifs_put_tcon.part.0+0x99/0x202 [cifs]
[ 301.682637] ? ida_free+0x99/0x10a
[ 301.682727] ? cifs_umount+0x3d/0x9d [cifs]
[ 301.682829] cifs_put_tlink+0x3a/0x50 [cifs]
[ 301.682929] cifs_umount+0x44/0x9d [cifs]
Fixes: 72e73c78c446 ("cifs: close the shared root handle on tree disconnect")
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Acked-by: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>
Reviewed-by: Aurelien Aptel <aaptel@xxxxxxxx>
Reviewed-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
Reported-and-tested-by: Arthur Marsh <arthur.marsh@xxxxxxxxxxxxxxxx>
--
Thanks,
Steve
From 281393894af9cc3f9483204475014e89d728987c Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@xxxxxxxxxxxxx>
Date: Mon, 9 Dec 2019 19:47:10 -0600
Subject: [PATCH 1/2] smb3: fix refcount underflow warning on unmount when no
directory leases
Fix refcount underflow warning when unmounting to servers which didn't grant
directory leases.
[ 301.680095] refcount_t: underflow; use-after-free.
[ 301.680192] WARNING: CPU: 1 PID: 3569 at lib/refcount.c:28
refcount_warn_saturate+0xb4/0xf3
...
[ 301.682139] Call Trace:
[ 301.682240] close_shroot+0x97/0xda [cifs]
[ 301.682351] SMB2_tdis+0x7c/0x176 [cifs]
[ 301.682456] ? _get_xid+0x58/0x91 [cifs]
[ 301.682563] cifs_put_tcon.part.0+0x99/0x202 [cifs]
[ 301.682637] ? ida_free+0x99/0x10a
[ 301.682727] ? cifs_umount+0x3d/0x9d [cifs]
[ 301.682829] cifs_put_tlink+0x3a/0x50 [cifs]
[ 301.682929] cifs_umount+0x44/0x9d [cifs]
Fixes: 72e73c78c446 ("cifs: close the shared root handle on tree disconnect")
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Acked-by: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>
Reviewed-by: Aurelien Aptel <aaptel@xxxxxxxx>
Reviewed-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
Reported-and-tested-by: Arthur Marsh <arthur.marsh@xxxxxxxxxxxxxxxx>
---
fs/cifs/smb2pdu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 0ab6b1200288..d2658f51ff60 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -1847,7 +1847,8 @@ SMB2_tdis(const unsigned int xid, struct cifs_tcon *tcon)
if ((tcon->need_reconnect) || (tcon->ses->need_reconnect))
return 0;
- close_shroot(&tcon->crfid);
+ if (tcon->crfid.is_valid)
+ close_shroot(&tcon->crfid);
rc = smb2_plain_req_init(SMB2_TREE_DISCONNECT, tcon, (void **) &req,
&total_len);
--
2.23.0
