Don't perform arithmetic on NULL pointers

When node is NULL when calling getparent() et al. they return NULL
but performing arithmetic on the NULL pointer is undefined.  Check
if 'node' or 'header' is NULL and skip the adjustment.

diff --git a/lib/dns/rbt.c b/lib/dns/rbt.c
index 64bdb25afe19415f6144648a05eb9d691db7cd31..0dd1fc43658ac01fa8bb7c04fee00caf341b6d68 100644 (file)
--- a/lib/dns/rbt.c
+++ b/lib/dns/rbt.c
@@ -168,6 +168,10 @@ serialize_nodes(FILE *file, dns_rbtnode_t *node, uintptr_t parent,
                dns_rbtdatawriter_t datawriter, void *writer_arg,
                uintptr_t *where, uint64_t *crc);
 
+#define ADJUST_ADDRESS(address, relative, header)        \
+       if (address != NULL && header != NULL) {         \
+               address += relative * (uintptr_t)header; \
+       }
 /*
  * The following functions allow you to get the actual address of a pointer
  * without having to use an if statement to check to see if that address is
@@ -176,7 +180,8 @@ serialize_nodes(FILE *file, dns_rbtnode_t *node, uintptr_t parent,
 static dns_rbtnode_t *
 getparent(dns_rbtnode_t *node, file_header_t *header) {
        char *adjusted_address = (char *)(node->parent);
-       adjusted_address += node->parent_is_relative * (uintptr_t)header;
+
+       ADJUST_ADDRESS(adjusted_address, node->parent_is_relative, header);
 
        return ((dns_rbtnode_t *)adjusted_address);
 }
@@ -184,7 +189,8 @@ getparent(dns_rbtnode_t *node, file_header_t *header) {
 static dns_rbtnode_t *
 getleft(dns_rbtnode_t *node, file_header_t *header) {
        char *adjusted_address = (char *)(node->left);
-       adjusted_address += node->left_is_relative * (uintptr_t)header;
+
+       ADJUST_ADDRESS(adjusted_address, node->left_is_relative, header);
 
        return ((dns_rbtnode_t *)adjusted_address);
 }
@@ -192,7 +198,8 @@ getleft(dns_rbtnode_t *node, file_header_t *header) {
 static dns_rbtnode_t *
 getright(dns_rbtnode_t *node, file_header_t *header) {
        char *adjusted_address = (char *)(node->right);
-       adjusted_address += node->right_is_relative * (uintptr_t)header;
+
+       ADJUST_ADDRESS(adjusted_address, node->right_is_relative, header);
 
        return ((dns_rbtnode_t *)adjusted_address);
 }
@@ -200,7 +207,8 @@ getright(dns_rbtnode_t *node, file_header_t *header) {
 static dns_rbtnode_t *
 getdown(dns_rbtnode_t *node, file_header_t *header) {
        char *adjusted_address = (char *)(node->down);
-       adjusted_address += node->down_is_relative * (uintptr_t)header;
+
+       ADJUST_ADDRESS(adjusted_address, node->down_is_relative, header);
 
        return ((dns_rbtnode_t *)adjusted_address);
 }
@@ -208,7 +216,8 @@ getdown(dns_rbtnode_t *node, file_header_t *header) {
 static dns_rbtnode_t *
 getdata(dns_rbtnode_t *node, file_header_t *header) {
        char *adjusted_address = (char *)(node->data);
-       adjusted_address += node->data_is_relative * (uintptr_t)header;
+
+       ADJUST_ADDRESS(adjusted_address, node->data_is_relative, header);
 
        return ((dns_rbtnode_t *)adjusted_address);
 }