From 2fefae47716d501aec41c1102f3fd4531f070b05 Mon Sep 17 00:00:00 2001
From: Remi Collet <remi@php.net>
Date: Tue, 19 Aug 2014 08:33:49 +0200
Subject: [PATCH] Fixed Sec Bug #67717 segfault in dns_get_record CVE-2014-3597
Incomplete fix for CVE-2014-4049
Check possible buffer overflow
- pass real buffer end to dn_expand calls
- check buffer len before each read
---
ext/standard/dns.c | 84 ++++++++++++++++++++++++++++++++++++++----------------
1 file changed, 60 insertions(+), 24 deletions(-)
diff --git a/ext/standard/dns.c b/ext/standard/dns.c
index 214a7dc..0b5e69c 100644
--- a/ext/standard/dns.c
+++ b/ext/standard/dns.c
@@ -412,8 +412,14 @@ PHP_FUNCTION(dns_check_record)
#if HAVE_FULL_DNS_FUNCS
+#define CHECKCP(n) do { \
+ if (cp + n > end) { \
+ return NULL; \
+ } \
+} while (0)
+
/* {{{ php_parserr */
-static u_char *php_parserr(u_char *cp, querybuf *answer, int type_to_fetch, int store, int raw, zval **subarray)
+static u_char *php_parserr(u_char *cp, u_char *end, querybuf *answer, int type_to_fetch, int store, int raw, zval **subarray)
{
u_short type, class, dlen;
u_long ttl;
@@ -425,16 +431,18 @@ static u_char *php_parserr(u_char *cp, querybuf *answer, int type_to_fetch, int
*subarray = NULL;
- n = dn_expand(answer->qb2, answer->qb2+65536, cp, name, sizeof(name) - 2);
+ n = dn_expand(answer->qb2, end, cp, name, sizeof(name) - 2);
if (n < 0) {
return NULL;
}
cp += n;
+ CHECKCP(10);
GETSHORT(type, cp);
GETSHORT(class, cp);
GETLONG(ttl, cp);
GETSHORT(dlen, cp);
+ CHECKCP(dlen);
if (type_to_fetch != T_ANY && type != type_to_fetch) {
cp += dlen;
return cp;
@@ -461,12 +469,14 @@ static u_char *php_parserr(u_char *cp, querybuf *answer, int type_to_fetch, int
switch (type) {
case DNS_T_A:
+ CHECKCP(4);
add_assoc_string(*subarray, "type", "A", 1);
snprintf(name, sizeof(name), "%d.%d.%d.%d", cp[0], cp[1], cp[2], cp[3]);
add_assoc_string(*subarray, "ip", name, 1);
cp += dlen;
break;
case DNS_T_MX:
+ CHECKCP(2);
add_assoc_string(*subarray, "type", "MX", 1);
GETSHORT(n, cp);
add_assoc_long(*subarray, "pri", n);
@@ -485,7 +495,7 @@ static u_char *php_parserr(u_char *cp, querybuf *answer, int type_to_fetch, int
if (type == DNS_T_PTR) {
add_assoc_string(*subarray, "type", "PTR", 1);
}
- n = dn_expand(answer->qb2, answer->qb2+65536, cp, name, (sizeof name) - 2);
+ n = dn_expand(answer->qb2, end, cp, name, (sizeof name) - 2);
if (n < 0) {
return NULL;
}
@@ -495,18 +505,22 @@ static u_char *php_parserr(u_char *cp, querybuf *answer, int type_to_fetch, int
case DNS_T_HINFO:
/* See RFC 1010 for values */
add_assoc_string(*subarray, "type", "HINFO", 1);
+ CHECKCP(1);
n = *cp & 0xFF;
cp++;
+ CHECKCP(n);
add_assoc_stringl(*subarray, "cpu", (char*)cp, n, 1);
cp += n;
+ CHECKCP(1);
n = *cp & 0xFF;
cp++;
+ CHECKCP(n);
add_assoc_stringl(*subarray, "os", (char*)cp, n, 1);
cp += n;
break;
case DNS_T_TXT:
{
- int ll = 0;
+ int l1 = 0, l2 = 0;
zval *entries = NULL;
add_assoc_string(*subarray, "type", "TXT", 1);
@@ -515,37 +529,41 @@ static u_char *php_parserr(u_char *cp, querybuf *answer, int type_to_fetch, int
MAKE_STD_ZVAL(entries);
array_init(entries);
- while (ll < dlen) {
- n = cp[ll];
- if ((ll + n) >= dlen) {
+ while (l1 < dlen) {
+ n = cp[l1];
+ if ((l1 + n) >= dlen) {
// Invalid chunk length, truncate
- n = dlen - (ll + 1);
+ n = dlen - (l1 + 1);
+ }
+ if (n) {
+ memcpy(tp + l2 , cp + l1 + 1, n);
+ add_next_index_stringl(entries, cp + l1 + 1, n, 1);
}
- memcpy(tp + ll , cp + ll + 1, n);
- add_next_index_stringl(entries, cp + ll + 1, n, 1);
- ll = ll + n + 1;
+ l1 = l1 + n + 1;
+ l2 = l2 + n;
}
- tp[dlen] = '\0';
+ tp[l2] = '\0';
cp += dlen;
- add_assoc_stringl(*subarray, "txt", tp, (dlen>0)?dlen - 1:0, 0);
+ add_assoc_stringl(*subarray, "txt", tp, l2, 0);
add_assoc_zval(*subarray, "entries", entries);
}
break;
case DNS_T_SOA:
add_assoc_string(*subarray, "type", "SOA", 1);
- n = dn_expand(answer->qb2, answer->qb2+65536, cp, name, (sizeof name) -2);
+ n = dn_expand(answer->qb2, end, cp, name, (sizeof name) -2);
if (n < 0) {
return NULL;
}
cp += n;
add_assoc_string(*subarray, "mname", name, 1);
- n = dn_expand(answer->qb2, answer->qb2+65536, cp, name, (sizeof name) -2);
+ n = dn_expand(answer->qb2, end, cp, name, (sizeof name) -2);
if (n < 0) {
return NULL;
}
cp += n;
add_assoc_string(*subarray, "rname", name, 1);
+ CHECKCP(5*4);
GETLONG(n, cp);
add_assoc_long(*subarray, "serial", n);
GETLONG(n, cp);
@@ -559,6 +577,7 @@ static u_char *php_parserr(u_char *cp, querybuf *answer, int type_to_fetch, int
break;
case DNS_T_AAAA:
tp = (u_char*)name;
+ CHECKCP(8*2);
for(i=0; i < 8; i++) {
GETSHORT(s, cp);
if (s != 0) {
@@ -593,6 +612,7 @@ static u_char *php_parserr(u_char *cp, querybuf *answer, int type_to_fetch, int
case DNS_T_A6:
p = cp;
add_assoc_string(*subarray, "type", "A6", 1);
+ CHECKCP(1);
n = ((int)cp[0]) & 0xFF;
cp++;
add_assoc_long(*subarray, "masklen", n);
@@ -628,6 +648,7 @@ static u_char *php_parserr(u_char *cp, querybuf *answer, int type_to_fetch, int
cp++;
}
for (i = (n + 8) / 16; i < 8; i++) {
+ CHECKCP(2);
GETSHORT(s, cp);
if (s != 0) {
if (tp > (u_char *)name) {
@@ -657,7 +678,7 @@ static u_char *php_parserr(u_char *cp, querybuf *answer, int type_to_fetch, int
tp[0] = '\0';
add_assoc_string(*subarray, "ipv6", name, 1);
if (cp < p + dlen) {
- n = dn_expand(answer->qb2, answer->qb2+65536, cp, name, (sizeof name) - 2);
+ n = dn_expand(answer->qb2, end, cp, name, (sizeof name) - 2);
if (n < 0) {
return NULL;
}
@@ -666,6 +687,7 @@ static u_char *php_parserr(u_char *cp, querybuf *answer, int type_to_fetch, int
}
break;
case DNS_T_SRV:
+ CHECKCP(3*2);
add_assoc_string(*subarray, "type", "SRV", 1);
GETSHORT(n, cp);
add_assoc_long(*subarray, "pri", n);
@@ -673,7 +695,7 @@ static u_char *php_parserr(u_char *cp, querybuf *answer, int type_to_fetch, int
add_assoc_long(*subarray, "weight", n);
GETSHORT(n, cp);
add_assoc_long(*subarray, "port", n);
- n = dn_expand(answer->qb2, answer->qb2+65536, cp, name, (sizeof name) - 2);
+ n = dn_expand(answer->qb2, end, cp, name, (sizeof name) - 2);
if (n < 0) {
return NULL;
}
@@ -681,21 +703,35 @@ static u_char *php_parserr(u_char *cp, querybuf *answer, int type_to_fetch, int
add_assoc_string(*subarray, "target", name, 1);
break;
case DNS_T_NAPTR:
+ CHECKCP(2*2);
add_assoc_string(*subarray, "type", "NAPTR", 1);
GETSHORT(n, cp);
add_assoc_long(*subarray, "order", n);
GETSHORT(n, cp);
add_assoc_long(*subarray, "pref", n);
+
+ CHECKCP(1);
n = (cp[0] & 0xFF);
- add_assoc_stringl(*subarray, "flags", (char*)++cp, n, 1);
+ cp++;
+ CHECKCP(n);
+ add_assoc_stringl(*subarray, "flags", (char*)cp, n, 1);
cp += n;
+
+ CHECKCP(1);
n = (cp[0] & 0xFF);
- add_assoc_stringl(*subarray, "services", (char*)++cp, n, 1);
+ cp++;
+ CHECKCP(n);
+ add_assoc_stringl(*subarray, "services", (char*)cp, n, 1);
cp += n;
+
+ CHECKCP(1);
n = (cp[0] & 0xFF);
- add_assoc_stringl(*subarray, "regex", (char*)++cp, n, 1);
+ cp++;
+ CHECKCP(n);
+ add_assoc_stringl(*subarray, "regex", (char*)cp, n, 1);
cp += n;
- n = dn_expand(answer->qb2, answer->qb2+65536, cp, name, (sizeof name) - 2);
+
+ n = dn_expand(answer->qb2, end, cp, name, (sizeof name) - 2);
if (n < 0) {
return NULL;
}
@@ -888,7 +924,7 @@ PHP_FUNCTION(dns_get_record)
while (an-- && cp && cp < end) {
zval *retval;
- cp = php_parserr(cp, &answer, type_to_fetch, store_results, raw, &retval);
+ cp = php_parserr(cp, end, &answer, type_to_fetch, store_results, raw, &retval);
if (retval != NULL && store_results) {
add_next_index_zval(return_value, retval);
}
@@ -901,7 +937,7 @@ PHP_FUNCTION(dns_get_record)
while (ns-- > 0 && cp && cp < end) {
zval *retval = NULL;
- cp = php_parserr(cp, &answer, DNS_T_ANY, authns != NULL, raw, &retval);
+ cp = php_parserr(cp, end, &answer, DNS_T_ANY, authns != NULL, raw, &retval);
if (retval != NULL) {
add_next_index_zval(authns, retval);
}
@@ -913,7 +949,7 @@ PHP_FUNCTION(dns_get_record)
while (ar-- > 0 && cp && cp < end) {
zval *retval = NULL;
- cp = php_parserr(cp, &answer, DNS_T_ANY, 1, raw, &retval);
+ cp = php_parserr(cp, end, &answer, DNS_T_ANY, 1, raw, &retval);
if (retval != NULL) {
add_next_index_zval(addtl, retval);
}
--
1.9.2