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From 094b5c3d904bae9aeb3206d9f3b8348926b84975 Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Sun, 21 Dec 2014 16:11:52 +0000
Subject: [PATCH] Fix crash in DNSSEC code when attempting to verify large RRs.
---
src/dnssec.c | 27 +++++++++++++++++++--------
diff --git a/src/dnssec.c b/src/dnssec.c
index 69bfc29..3208ac7 100644
--- a/src/dnssec.c
+++ b/src/dnssec.c
@@ -456,16 +456,27 @@ static u16 *get_desc(int type)
/* Return bytes of canonicalised rdata, when the return value is zero, the remaining
data, pointed to by *p, should be used raw. */
-static int get_rdata(struct dns_header *header, size_t plen, unsigned char *end, char *buff,
+static int get_rdata(struct dns_header *header, size_t plen, unsigned char *end, char *buff, int bufflen,
unsigned char **p, u16 **desc)
{
int d = **desc;
- (*desc)++;
-
/* No more data needs mangling */
if (d == (u16)-1)
- return 0;
+ {
+ /* If there's more data than we have space for, just return what fits,
+ we'll get called again for more chunks */
+ if (end - *p > bufflen)
+ {
+ memcpy(buff, *p, bufflen);
+ *p += bufflen;
+ return bufflen;
+ }
+
+ return 0;
+ }
+
+ (*desc)++;
if (d == 0 && extract_name(header, plen, p, buff, 1, 0))
/* domain-name, canonicalise */
@@ -560,7 +571,7 @@ static void sort_rrset(struct dns_header *header, size_t plen, u16 *rr_desc, int
if (left1 != 0)
memmove(buff1, buff1 + len1 - left1, left1);
- if ((len1 = get_rdata(header, plen, end1, buff1 + left1, &p1, &dp1)) == 0)
+ if ((len1 = get_rdata(header, plen, end1, buff1 + left1, MAXDNAME - left1, &p1, &dp1)) == 0)
{
quit = 1;
len1 = end1 - p1;
@@ -571,7 +582,7 @@ static void sort_rrset(struct dns_header *header, size_t plen, u16 *rr_desc, int
if (left2 != 0)
memmove(buff2, buff2 + len2 - left2, left2);
- if ((len2 = get_rdata(header, plen, end2, buff2 + left2, &p2, &dp2)) == 0)
+ if ((len2 = get_rdata(header, plen, end2, buff2 + left2, MAXDNAME - left2, &p2, &dp2)) == 0)
{
quit = 1;
len2 = end2 - p2;
@@ -808,7 +819,7 @@ static int validate_rrset(time_t now, struct dns_header *header, size_t plen, in
/* canonicalise rdata and calculate length of same, use name buffer as workspace */
cp = p;
dp = rr_desc;
- for (len = 0; (seg = get_rdata(header, plen, end, name, &cp, &dp)) != 0; len += seg);
+ for (len = 0; (seg = get_rdata(header, plen, end, name, MAXDNAME, &cp, &dp)) != 0; len += seg);
len += end - cp;
len = htons(len);
hash->update(ctx, 2, (unsigned char *)&len);
@@ -816,7 +827,7 @@ static int validate_rrset(time_t now, struct dns_header *header, size_t plen, in
/* Now canonicalise again and digest. */
cp = p;
dp = rr_desc;
- while ((seg = get_rdata(header, plen, end, name, &cp, &dp)))
+ while ((seg = get_rdata(header, plen, end, name, MAXDNAME, &cp, &dp)))
hash->update(ctx, seg, (unsigned char *)name);
if (cp != end)
hash->update(ctx, end - cp, cp);
--
2.1.3
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