Security fixes from bind 4.9.7-REL.
[kopensolaris-gnu/glibc.git] / resolv / gethnamaddr.c
index 4c8180f..3272dbd 100644 (file)
@@ -160,6 +160,24 @@ dprintf(msg, num)
 # define dprintf(msg, num) /*nada*/
 #endif
 
+#define BOUNDED_INCR(x) \
+       do { \
+               cp += x; \
+               if (cp > eom) { \
+                       __set_h_errno (NO_RECOVERY); \
+                       return (NULL); \
+               } \
+       } while (0)
+
+#define BOUNDS_CHECK(ptr, count) \
+       do { \
+               if ((ptr) + (count) > eom) { \
+                       __set_h_errno (NO_RECOVERY); \
+                       return (NULL); \
+               } \
+       } while (0)
+
+
 static struct hostent *
 getanswer(answer, anslen, qname, qtype)
        const querybuf *answer;
@@ -170,7 +188,7 @@ getanswer(answer, anslen, qname, qtype)
        register const HEADER *hp;
        register const u_char *cp;
        register int n;
-       const u_char *eom;
+       const u_char *eom, *erdata;
        char *bp, **ap, **hap;
        int type, class, buflen, ancount, qdcount;
        int haveanswer, had_error;
@@ -201,7 +219,8 @@ getanswer(answer, anslen, qname, qtype)
        qdcount = ntohs(hp->qdcount);
        bp = hostbuf;
        buflen = sizeof hostbuf;
-       cp = answer->buf + HFIXEDSZ;
+       cp = answer->buf;
+       BOUNDED_INCR(HFIXEDSZ);
        if (qdcount != 1) {
                __set_h_errno (NO_RECOVERY);
                return (NULL);
@@ -211,7 +230,7 @@ getanswer(answer, anslen, qname, qtype)
                __set_h_errno (NO_RECOVERY);
                return (NULL);
        }
-       cp += n + QFIXEDSZ;
+       BOUNDED_INCR(n + QFIXEDSZ);
        if (qtype == T_A || qtype == T_AAAA) {
                /* res_send() has already verified that the query name is the
                 * same as the one we sent; this just gets the expanded name
@@ -243,12 +262,15 @@ getanswer(answer, anslen, qname, qtype)
                        continue;
                }
                cp += n;                        /* name */
+               BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
                type = _getshort(cp);
                cp += INT16SZ;                  /* type */
                class = _getshort(cp);
                cp += INT16SZ + INT32SZ;        /* class, TTL */
                n = _getshort(cp);
                cp += INT16SZ;                  /* len */
+               BOUNDS_CHECK(cp, n);
+               erdata = cp + n;
                if (class != C_IN) {
                        /* XXX - debug? syslog? */
                        cp += n;
@@ -263,6 +285,10 @@ getanswer(answer, anslen, qname, qtype)
                                continue;
                        }
                        cp += n;
+                       if (cp != erdata) {
+                               __set_h_errno (NO_RECOVERY);
+                               return (NULL);
+                       }
                        /* Store alias. */
                        *ap++ = bp;
                        n = strlen(bp) + 1;     /* for the \0 */
@@ -291,6 +317,10 @@ getanswer(answer, anslen, qname, qtype)
                                continue;
                        }
                        cp += n;
+                       if (cp != erdata) {
+                               __set_h_errno (NO_RECOVERY);
+                               return (NULL);
+                       }
                        /* Get canonical name. */
                        n = strlen(tbuf) + 1;   /* for the \0 */
                        if (n > buflen || n >= MAXHOSTNAMELEN) {
@@ -326,6 +356,10 @@ getanswer(answer, anslen, qname, qtype)
                        }
 #if MULTI_PTRS_ARE_ALIASES
                        cp += n;
+                       if (cp != erdata) {
+                               __set_h_errno (NO_RECOVERY);
+                               return (NULL);
+                       }
                        if (!haveanswer)
                                host.h_name = bp;
                        else if (ap < &host_aliases[MAXALIASES-1])
@@ -397,6 +431,10 @@ getanswer(answer, anslen, qname, qtype)
                        bp += n;
                        buflen -= n;
                        cp += n;
+                       if (cp != erdata) {
+                               __set_h_errno (NO_RECOVERY);
+                               return (NULL);
+                       }
                        break;
                default:
                        abort();