[PATCH 4.4 53/60] CIFS: Fix a possible memory corruption in push locks

From: Greg Kroah-Hartman
Date: Wed Jan 04 2017 - 15:51:42 EST


4.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>

commit e3d240e9d505fc67f8f8735836df97a794bbd946 upstream.

If maxBuf is not 0 but less than a size of SMB2 lock structure
we can end up with a memory corruption.

Signed-off-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
fs/cifs/smb2file.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/cifs/smb2file.c
+++ b/fs/cifs/smb2file.c
@@ -260,7 +260,7 @@ smb2_push_mandatory_locks(struct cifsFil
* and check it for zero before using.
*/
max_buf = tlink_tcon(cfile->tlink)->ses->server->maxBuf;
- if (!max_buf) {
+ if (max_buf < sizeof(struct smb2_lock_element)) {
free_xid(xid);
return -EINVAL;
}