CIFS: fix use-after-free of the lease keys
authorAurelien Aptel <aaptel@suse.com>
Thu, 31 Jan 2019 12:46:07 +0000 (13:46 +0100)
committerSteve French <stfrench@microsoft.com>
Thu, 31 Jan 2019 13:03:20 +0000 (07:03 -0600)
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>
fs/cifs/smb2pdu.c

index ef52d66424314f85ea5de5689bd31202937b6709..77b3aaa39b35c0c6dc1c96c8bdf0542fa1bf98bc 100644 (file)
@@ -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,