[PATCH 1/4] svcrpc: fix gss-proxy NULL dereference in some error cases

["J. Bruce Fields" <bfields@redhat.com>]

From: "J. Bruce Fields" <bfields@redhat.com>

We depend on the xdr decoder to set this pointer, but if we error out
before we decode this piece it could be left NULL.

I think this is probably tough to hit without a buggy gss-proxy.

Reported-by: Andi Kleen <andi@firstfloor.org>
Cc: Simo Sorce <simo@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---
 net/sunrpc/auth_gss/gss_rpc_upcall.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/sunrpc/auth_gss/gss_rpc_upcall.c b/net/sunrpc/auth_gss/gss_rpc_upcall.c
index f1eb0d1..458f85e 100644
--- a/net/sunrpc/auth_gss/gss_rpc_upcall.c
+++ b/net/sunrpc/auth_gss/gss_rpc_upcall.c
@@ -298,7 +298,8 @@ int gssp_accept_sec_context_upcall(struct net *net,
 	if (res.context_handle) {
 		data->out_handle = rctxh.exported_context_token;
 		data->mech_oid.len = rctxh.mech.len;
-		memcpy(data->mech_oid.data, rctxh.mech.data,
+		if (rctxh.mech.data)
+			memcpy(data->mech_oid.data, rctxh.mech.data,
 						data->mech_oid.len);
 		client_name = rctxh.src_name.display_name;
 	}
-- 
1.7.9.5