[PATCH 3.11 057/137] dns_resolver: assure that dns_query() result is null-terminated

[Luis Henriques]

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

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

From: =?UTF-8?q?Manuel=20Sch=C3=B6lling?= <manuel.schoelling at gmx.de>

commit 84a7c0b1db1c17d5ded8d3800228a608e1070b40 upstream.

dns_query() credulously assumes that keys are null-terminated and
returns a copy of a memory block that is off by one.

Signed-off-by: Manuel Schölling <manuel.schoelling at gmx.de>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/dns_resolver/dns_query.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/dns_resolver/dns_query.c b/net/dns_resolver/dns_query.c
index c32be292c7e3..ede0e2d7412e 100644
--- a/net/dns_resolver/dns_query.c
+++ b/net/dns_resolver/dns_query.c
@@ -150,7 +150,9 @@ int dns_query(const char *type, const char *name, size_t namelen,
 	if (!*_result)
 		goto put;
 
-	memcpy(*_result, upayload->data, len + 1);
+	memcpy(*_result, upayload->data, len);
+	*_result[len] = '\0';
+
 	if (_expiry)
 		*_expiry = rkey->expiry;
 
-- 
1.9.1