isisd: fix null pointer dereference when parsing LSP

In some extraordinary circumstances an LSP might not have any
TLV. Add a null check to prevent a crash when that happens.

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>

diff --git a/isisd/isis_tlvs.c b/isisd/isis_tlvs.c
index af419961d56fb7974306de28ec3b6a23a20e7471..a97c19a8bc54fa4e19b37ff9eb7f931a69e0df65 100644 (file)
--- a/isisd/isis_tlvs.c
+++ b/isisd/isis_tlvs.c
@@ -4850,7 +4850,7 @@ void isis_tlvs_add_spine_leaf(struct isis_tlvs *tlvs, uint8_t tier,
 struct isis_mt_router_info *
 isis_tlvs_lookup_mt_router_info(struct isis_tlvs *tlvs, uint16_t mtid)
 {
-       if (tlvs->mt_router_info_empty)
+       if (!tlvs || tlvs->mt_router_info_empty)
                return NULL;
 
        struct isis_mt_router_info *rv;