staticd: Fix crash when allocating SIDs without parent locator

In same cases, it may happen staticd attempts to allocate a SID when it
does not know about the parent locator yet.
In this case, the locator pointer stored inside the SID data structure
is NULL. When `static_zebra_request_srv6_sid` attempts to dereference
the locator pointer, we get a NULL pointer dereference crash.

This commit adds a check to prevent the crash from happening.

If the locator pointer is NULL, it means that staticd is not aware
about the parent locator yet. Then, staticd should call
`static_zebra_srv6_manager_get_locator()` to get the locator from SRv6
Manager. Once staticd receives the requested locator, the existing
callback `static_zebra_process_srv6_locator_internal()` will take care
of retrying to allocate the SID.

Signed-off-by: Carmine Scarpitta <[email protected]>

Author: cscarpitta

staticd/static_zebra.c

@@ -921,6 +921,11 @@ extern void static_zebra_request_srv6_sid(struct static_srv6_sid *sid)
 	if (!sid)
 		return;
 
+	if (!sid->locator) {
+		static_zebra_srv6_manager_get_locator(sid->locator_name);
+		return;
+	}
+
 	/* convert `srv6_endpoint_behavior_codepoint` to `seg6local_action_t` */
 	switch (sid->behavior) {
 	case SRV6_ENDPOINT_BEHAVIOR_END: