From 0f03071080e7fa68433b322359d46abaca2cc5ad Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Petr=20Men=C5=A1=C3=ADk?= <pemensik@redhat.com>

Date: Wed, 16 Jan 2019 16:27:33 +0100

Subject: [PATCH] Fix possible crash when loading corrupted file

Some values passes internal triggers by coincidence. Fix the check and

check also first_node_offset before even passing it further.

---

 lib/dns/rbt.c | 4 +++-

 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/dns/rbt.c b/lib/dns/rbt.c

index 5aee5f6..7f2c2d2 100644

--- a/lib/dns/rbt.c

+++ b/lib/dns/rbt.c

@@ -945,7 +945,9 @@ dns_rbt_deserialize_tree(void *base_address, size_t filesize,

 	rbt->root = (dns_rbtnode_t *)((char *)base_address + header_offset +

 				      header->first_node_offset);

-	if ((header->nodecount * sizeof(dns_rbtnode_t)) > filesize) {

+	if ((header->nodecount * sizeof(dns_rbtnode_t)) > filesize

+	    || header->first_node_offset > filesize) {

+

 		result = ISC_R_INVALIDFILE;

 		goto cleanup;

 	}

-- 

2.31.1