af_key: add __GFP_ZERO flag for compose_sadb_supported in function pfkey_register

Add __GFP_ZERO flag for compose_sadb_supported in function pfkey_register
to initialize the buffer of supp_skb to fix a kernel-info-leak issue.
1) Function pfkey_register calls compose_sadb_supported to request
a sk_buff. 2) compose_sadb_supported calls alloc_sbk to allocate
a sk_buff, but it doesn't zero it. 3) If auth_len is greater 0, then
compose_sadb_supported treats the memory as a struct sadb_supported and
begins to initialize. But it just initializes the field sadb_supported_len
and field sadb_supported_exttype without field sadb_supported_reserved.

Reported-by: TCS Robot <tcs_robot@tencent.com>
Signed-off-by: Haimin Zhang <tcs_kernel@tencent.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

diff --git a/net/key/af_key.c b/net/key/af_key.c
index 9bf52a0..fd51db3 100644 (file)
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -1699,7 +1699,7 @@ static int pfkey_register(struct sock *sk, struct sk_buff *skb, const struct sad
 
        xfrm_probe_algs();
 
-       supp_skb = compose_sadb_supported(hdr, GFP_KERNEL);
+       supp_skb = compose_sadb_supported(hdr, GFP_KERNEL | __GFP_ZERO);
        if (!supp_skb) {
                if (hdr->sadb_msg_satype != SADB_SATYPE_UNSPEC)
                        pfk->registered &= ~(1<<hdr->sadb_msg_satype);