Fail gracefully when set_dhcp_option() is called with options==NULL.

[people/xl0/gpxe.git] / src / net / dhcpopts.c

diff --git a/src/net/dhcpopts.c b/src/net/dhcpopts.c
index c906b19..e847c81 100644 (file)
--- a/src/net/dhcpopts.c
+++ b/src/net/dhcpopts.c
@@ -409,12 +409,16 @@ struct dhcp_option * set_dhcp_option ( struct dhcp_option_block *options,
                                       const void *data, size_t len ) {
        static const uint8_t empty_encapsulator[] = { DHCP_END };
        struct dhcp_option *option;
-       void *insertion_point = options->data;
+       void *insertion_point;
        struct dhcp_option *encapsulator = NULL;
        unsigned int encap_tag = DHCP_ENCAPSULATOR ( tag );
        size_t old_len = 0;
        size_t new_len = ( len ? ( len + DHCP_OPTION_HEADER_LEN ) : 0 );
 
+       /* Return NULL if no options block specified */
+       if ( ! options )
+               return NULL;
+
        /* Find old instance of this option, if any */
        option = find_dhcp_option_with_encap ( options, tag, &encapsulator );
        if ( option ) {
@@ -428,6 +432,7 @@ struct dhcp_option * set_dhcp_option ( struct dhcp_option_block *options,
        }
        
        /* Ensure that encapsulator exists, if required */
+       insertion_point = options->data;
        if ( DHCP_IS_ENCAP_OPT ( tag ) ) {
                if ( ! encapsulator )
                        encapsulator = set_dhcp_option ( options, encap_tag,