CIFS: fix use-after-free of the lease keys
The request buffers are freed right before copying the pointers.
Use the func args instead which are identical and still valid.
Simple reproducer (requires KASAN enabled) on a cifs mount:
echo foo > foo ; tail -f foo & rm foo
Cc: <stable@vger.kernel.org> # 4.20
Fixes: 179e44d49c2f ("smb3: add tracepoint for sending lease break responses to server")
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Paulo Alcantara <palcantara@suse.de>
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index ef52d66..77b3aaa3 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -4441,8 +4441,8 @@ SMB2_lease_break(const unsigned int xid, struct cifs_tcon *tcon,
rc = cifs_send_recv(xid, ses, &rqst, &resp_buf_type, flags, &rsp_iov);
cifs_small_buf_release(req);
- please_key_low = (__u64 *)req->LeaseKey;
- please_key_high = (__u64 *)(req->LeaseKey+8);
+ please_key_low = (__u64 *)lease_key;
+ please_key_high = (__u64 *)(lease_key+8);
if (rc) {
cifs_stats_fail_inc(tcon, SMB2_OPLOCK_BREAK_HE);
trace_smb3_lease_err(le32_to_cpu(lease_state), tcon->tid,