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

diff --git a/ext/standard/dns.c b/ext/standard/dns.c
index 214a7dc7e92faf55a2f69be27adbb8ea99ab403f..0b5e69ca58cc13b9f4e7f78dbac0c89aa5fb5e26 100644 (file)
--- 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);
                                        }