[ 078/108] xfrm_user: fix info leak in copy_to_user_auth()

[Ben Hutchings]

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

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

From: Mathias Krause <minipli@xxxxxxxxxxxxxx>

[ Upstream commit 4c87308bdea31a7b4828a51f6156e6f721a1fcc9 ]

copy_to_user_auth() fails to initialize the remainder of alg_name and
therefore discloses up to 54 bytes of heap memory via netlink to
userland.

Use strncpy() instead of strcpy() to fill the trailing bytes of alg_name
with null bytes.

Signed-off-by: Mathias Krause <minipli@xxxxxxxxxxxxxx>
Acked-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 net/xfrm/xfrm_user.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 1221b77..7f53c82 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -742,7 +742,7 @@ static int copy_to_user_auth(struct xfrm_algo_auth *auth, struct sk_buff *skb)
 		return -EMSGSIZE;
 
 	algo = nla_data(nla);
-	strcpy(algo->alg_name, auth->alg_name);
+	strncpy(algo->alg_name, auth->alg_name, sizeof(algo->alg_name));
 	memcpy(algo->alg_key, auth->alg_key, (auth->alg_key_len + 7) / 8);
 	algo->alg_key_len = auth->alg_key_len;
 


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