From b04cb88462863d762093760ffcfe1946200e30f5 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ond=C5=99ej=20Sur=C3=BD?= Date: Thu, 7 Jan 2021 10:44:46 +0100 Subject: [PATCH] Fix off-by-one bug in ISC SPNEGO implementation The ISC SPNEGO implementation is based on mod_auth_kerb code. When CVE-2006-5989 was disclosed, the relevant fix was not applied to the BIND 9 codebase, making the latter vulnerable to the aforementioned flaw when "tkey-gssapi-keytab" or "tkey-gssapi-credential" is set in named.conf. The original description of CVE-2006-5989 was: Off-by-one error in the der_get_oid function in mod_auth_kerb 5.0 allows remote attackers to cause a denial of service (crash) via a crafted Kerberos message that triggers a heap-based buffer overflow in the component array. Later research revealed that this flaw also theoretically enables remote code execution, though achieving the latter in real-world conditions is currently deemed very difficult. This vulnerability was responsibly reported as ZDI-CAN-12302 ("ISC BIND TKEY Query Heap-based Buffer Overflow Remote Code Execution Vulnerability") by Trend Micro Zero Day Initiative. --- lib/dns/spnego.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/dns/spnego.c b/lib/dns/spnego.c index e61d1c600f..753dc8049f 100644 --- a/lib/dns/spnego.c +++ b/lib/dns/spnego.c @@ -848,7 +848,7 @@ der_get_oid(const unsigned char *p, size_t len, oid *data, size_t *size) { return (ASN1_OVERRUN); } - data->components = malloc(len * sizeof(*data->components)); + data->components = malloc((len + 1) * sizeof(*data->components)); if (data->components == NULL) { return (ENOMEM); } -- 2.26.2