svcrpc: fix gss-proxy NULL dereference in some error cases

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>

diff --git a/net/sunrpc/auth_gss/gss_rpc_upcall.c b/net/sunrpc/auth_gss/gss_rpc_upcall.c
index f1eb0d16666c2750b0001d923fabbd572f2cbe7d..458f85e9b0ba088575a72ef6dd6ff8d21484d290 100644 (file)
--- 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;
        }