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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
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remicollet committed Aug 19, 2014
1 parent 1504f7d commit 2fefae47716d501aec41c1102f3fd4531f070b05
Showing with 60 additions and 24 deletions.
  1. +60 −24 ext/standard/dns.c
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@@ -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;
}
@@ -666,36 +687,51 @@ 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);
GETSHORT(n, cp);
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;
}
cp += n;
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);
}

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