cifs: fix parsing of hostname in dfs referrals

commit ba03864872691c0bb580a7fb47388da337ef4aa2 upstream.

The DFS referral parsing code does a memchr() call to find the '\\'
delimiter that separates the hostname in the referral UNC from the
sharename. It then uses that value to set the length of the hostname via
pointer subtraction.  Instead of subtracting the start of the hostname
however, it subtracts the start of the UNC, which causes the code to
pass in a hostname length that is 2 bytes too long.

Regression introduced in commit 1a4240f4.

Reported-and-Tested-by: Robbert Kouprie <robbert@exx.nl>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: Wang Lei <wang840925@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/cifs/dns_resolve.c b/fs/cifs/dns_resolve.c
index 0eb87026cad3a4bf1050af0d2409ca0bfd7c928a..548f06230a6df50063b5c747b77330c4815fdd2e 100644 (file)
--- a/fs/cifs/dns_resolve.c
+++ b/fs/cifs/dns_resolve.c
@@ -66,7 +66,7 @@ dns_resolve_server_name_to_ip(const char *unc, char **ip_addr)
        /* Search for server name delimiter */
        sep = memchr(hostname, '\\', len);
        if (sep)
-               len = sep - unc;
+               len = sep - hostname;
        else
                cFYI(1, "%s: probably server name is whole unc: %s",
                     __func__, unc);