CVE-2016-10739: getaddrinfo: Fully parse IPv4 address strings [BZ #20018]

The IPv4 address parser in the getaddrinfo function is changed so that
it does not ignore trailing whitespace and all characters after it.
For backwards compatibility, the getaddrinfo function still recognizes
legacy name syntax, such as 192.000.002.010 interpreted as 192.0.2.8
(octal).

This commit does not change the behavior of inet_addr and inet_aton.
gethostbyname already had additional sanity checks (but is switched
over to the new __inet_aton_exact function for completeness as well).

To avoid sending the problematic query names over DNS, commit
6ca53a2453598804a2559a548a08424fca96434a ("resolv: Do not send queries
for non-host-names in nss_dns [BZ #24112]") is needed.

15 files changed, 455 insertions, 40 deletions

diff --git a/ChangeLog b/ChangeLog
index 834fca6fdc..bbf38b690a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,36 @@
+2019-01-21  Florian Weimer  <fweimer@redhat.com>
+
+	[BZ #20018]
+	CVE-2016-10739
+	resolv: Reject trailing characters in host names
+	* include/arpa/inet.h (__inet_aton_exact): Declare.
+	(inet_aton): Remove hidden prototype.  No longer used internally.
+	* nscd/gai.c (__inet_aton): Do not define.
+	* nscd/gethstbynm3_r.c (__inet_aton): Likewise.
+	* nss/digits_dots.c (__inet_aton): Likewise.
+	(__nss_hostname_digits_dots_context): Call __inet_aton_exact.
+	* resolv/Makefile (tests-internal): Add tst-inet_aton_exact.
+	(tests): Add tst-resolv-nondecimal, tst-resolv-trailing.
+	(tst-resolv-nondecimal): Link with libresolv.so and libpthread.
+	(tst-resolv-trailing): Likewise.
+	* resolv/Versions (GLIBC_PRIVATE): Export __inet_aton_exact from
+	libc.
+	* resolv/inet_addr.c (inet_aton_end): Remame from __inet_aton.
+	Make static.  Add endp parameter.
+	(__inet_aton_exact): New function.
+	(__inet_aton_ignore_trailing): New function, aliased to inet_aton.
+	(__inet_addr): Call inet_aton_end.
+	* resolv/res_init.c (res_vinit_1): Truncate nameserver for IPv4,
+	not just IPv6.  Call __inet_aton_exact.
+	* resolv/tst-aton.c: Switch to <support/test-driver.c>.
+	(tests): Make const.  Add additional test cases with trailing
+	characters.
+	(do_test): Use array_length.
+	* resolv/tst-inet_aton_exact.c: New file.
+	* resolv/tst-resolv-trailing.c: Likewise.
+	* resolv/tst-resolv-nondecimal.c: Likewise.
+	* sysdeps/posix/getaddrinfo.c (gaih_inet): Call __inet_aton_exact.
+
 2019-01-21  H.J. Lu  <hongjiu.lu@intel.com>
 
 	[BZ# 24097]
diff --git a/NEWS b/NEWS
index 7b3af113bf..d863d80f3a 100644
--- a/NEWS
+++ b/NEWS
@@ -107,6 +107,10 @@ Security related changes:
   in the assembly string/memory functions would cause a buffer overflow.
   Reported by H.J. Lu.
 
+  CVE-2016-10739: The getaddrinfo function could successfully parse IPv4
+  addresses with arbitrary trailing characters, potentially leading to data
+  or command injection issues in applications.
+
 The following bugs are resolved with this release:
 
   [The release manager will add the list generated by
diff --git a/include/arpa/inet.h b/include/arpa/inet.h
index c3f28f2baa..19aec74275 100644
--- a/include/arpa/inet.h
+++ b/include/arpa/inet.h
@@ -1,10 +1,10 @@
 #include <inet/arpa/inet.h>
 
 #ifndef _ISOMAC
-extern int __inet_aton (const char *__cp, struct in_addr *__inp);
-libc_hidden_proto (__inet_aton)
+/* Variant of inet_aton which rejects trailing garbage.  */
+extern int __inet_aton_exact (const char *__cp, struct in_addr *__inp);
+libc_hidden_proto (__inet_aton_exact)
 
-libc_hidden_proto (inet_aton)
 libc_hidden_proto (inet_ntop)
 libc_hidden_proto (inet_pton)
 extern __typeof (inet_pton) __inet_pton;
diff --git a/nscd/gai.c b/nscd/gai.c
index fd4e8e092f..801d304d47 100644
--- a/nscd/gai.c
+++ b/nscd/gai.c
@@ -19,7 +19,6 @@
 
 /* This file uses the getaddrinfo code but it compiles it without NSCD
    support.  We just need a few symbol renames.  */
-#define __inet_aton inet_aton
 #define __ioctl ioctl
 #define __getsockname getsockname
 #define __socket socket
diff --git a/nscd/gethstbynm3_r.c b/nscd/gethstbynm3_r.c
index 9f70a86a58..ff594b6d27 100644
--- a/nscd/gethstbynm3_r.c
+++ b/nscd/gethstbynm3_r.c
@@ -38,8 +38,6 @@
 #define HAVE_LOOKUP_BUFFER	1
 #define HAVE_AF			1
 
-#define __inet_aton inet_aton
-
 /* We are nscd, so we don't want to be talking to ourselves.  */
 #undef	USE_NSCD
 
diff --git a/nss/digits_dots.c b/nss/digits_dots.c
index 95015896a4..440d9955d2 100644
--- a/nss/digits_dots.c
+++ b/nss/digits_dots.c
@@ -29,7 +29,6 @@
 #include "nsswitch.h"
 
 #ifdef USE_NSCD
-# define inet_aton __inet_aton
 # include <nscd/nscd_proto.h>
 #endif
 
@@ -160,7 +159,7 @@ __nss_hostname_digits_dots_context (struct resolv_context *ctx,
 		     255.255.255.255?  The test below will succeed
 		     spuriously... ???  */
 		  if (af == AF_INET)
-		    ok = __inet_aton (name, (struct in_addr *) host_addr);
+		    ok = __inet_aton_exact (name, (struct in_addr *) host_addr);
 		  else
 		    {
 		      assert (af == AF_INET6);
diff --git a/resolv/Makefile b/resolv/Makefile
index 450e171b01..8f22e6a154 100644
--- a/resolv/Makefile
+++ b/resolv/Makefile
@@ -34,6 +34,9 @@ routines := herror inet_addr inet_ntop inet_pton nsap_addr res_init \
 tests = tst-aton tst-leaks tst-inet_ntop
 xtests = tst-leaks2
 
+tests-internal += tst-inet_aton_exact
+
+
 generate := mtrace-tst-leaks.out tst-leaks.mtrace tst-leaks2.mtrace
 
 extra-libs := libresolv libnss_dns
@@ -54,8 +57,10 @@ tests += \
   tst-resolv-binary \
   tst-resolv-edns \
   tst-resolv-network \
+  tst-resolv-nondecimal \
   tst-resolv-res_init-multi \
   tst-resolv-search \
+  tst-resolv-trailing \
 
 # These tests need libdl.
 ifeq (yes,$(build-shared))
@@ -190,9 +195,11 @@ $(objpfx)tst-resolv-res_init-multi: $(objpfx)libresolv.so \
   $(shared-thread-library)
 $(objpfx)tst-resolv-res_init-thread: $(libdl) $(objpfx)libresolv.so \
   $(shared-thread-library)
+$(objpfx)tst-resolv-nondecimal: $(objpfx)libresolv.so $(shared-thread-library)
 $(objpfx)tst-resolv-qtypes: $(objpfx)libresolv.so $(shared-thread-library)
 $(objpfx)tst-resolv-rotate: $(objpfx)libresolv.so $(shared-thread-library)
 $(objpfx)tst-resolv-search: $(objpfx)libresolv.so $(shared-thread-library)
+$(objpfx)tst-resolv-trailing: $(objpfx)libresolv.so $(shared-thread-library)
 $(objpfx)tst-resolv-threads: \
   $(libdl) $(objpfx)libresolv.so $(shared-thread-library)
 $(objpfx)tst-resolv-canonname: \
diff --git a/resolv/Versions b/resolv/Versions
index b05778d965..9a82704af7 100644
--- a/resolv/Versions
+++ b/resolv/Versions
@@ -27,6 +27,7 @@ libc {
     __h_errno; __resp;
 
     __res_iclose;
+    __inet_aton_exact;
     __inet_pton_length;
     __resolv_context_get;
     __resolv_context_get_preinit;
diff --git a/resolv/inet_addr.c b/resolv/inet_addr.c
index 32f58b0e13..41b6166a5b 100644
--- a/resolv/inet_addr.c
+++ b/resolv/inet_addr.c
@@ -96,26 +96,14 @@
 #include <limits.h>
 #include <errno.h>
 
-/* ASCII IPv4 Internet address interpretation routine.  The value
-   returned is in network order.  */
-in_addr_t
-__inet_addr (const char *cp)
-{
-  struct in_addr val;
-
-  if (__inet_aton (cp, &val))
-    return val.s_addr;
-  return INADDR_NONE;
-}
-weak_alias (__inet_addr, inet_addr)
-
 /* Check whether "cp" is a valid ASCII representation of an IPv4
    Internet address and convert it to a binary address.  Returns 1 if
    the address is valid, 0 if not.  This replaces inet_addr, the
    return value from which cannot distinguish between failure and a
-   local broadcast address.  */
-int
-__inet_aton (const char *cp, struct in_addr *addr)
+   local broadcast address.  Write a pointer to the first
+   non-converted character to *endp.  */
+static int
+inet_aton_end (const char *cp, struct in_addr *addr, const char **endp)
 {
   static const in_addr_t max[4] = { 0xffffffff, 0xffffff, 0xffff, 0xff };
   in_addr_t val;
@@ -180,6 +168,7 @@ __inet_aton (const char *cp, struct in_addr *addr)
 
   if (addr != NULL)
     addr->s_addr = res.word | htonl (val);
+  *endp = cp;
 
   __set_errno (saved_errno);
   return 1;
@@ -188,6 +177,41 @@ __inet_aton (const char *cp, struct in_addr *addr)
   __set_errno (saved_errno);
   return 0;
 }
-weak_alias (__inet_aton, inet_aton)
-libc_hidden_def (__inet_aton)
-libc_hidden_weak (inet_aton)
+
+int
+__inet_aton_exact (const char *cp, struct in_addr *addr)
+{
+  struct in_addr val;
+  const char *endp;
+  /* Check that inet_aton_end parsed the entire string.  */
+  if (inet_aton_end (cp, &val, &endp) != 0 && *endp == 0)
+    {
+      *addr = val;
+      return 1;
+    }
+  else
+    return 0;
+}
+libc_hidden_def (__inet_aton_exact)
+
+/* inet_aton ignores trailing garbage.  */
+int
+__inet_aton_ignore_trailing (const char *cp, struct in_addr *addr)
+{
+  const char *endp;
+  return  inet_aton_end (cp, addr, &endp);
+}
+weak_alias (__inet_aton_ignore_trailing, inet_aton)
+
+/* ASCII IPv4 Internet address interpretation routine.  The value
+   returned is in network order.  */
+in_addr_t
+__inet_addr (const char *cp)
+{
+  struct in_addr val;
+  const char *endp;
+  if (inet_aton_end (cp, &val, &endp))
+    return val.s_addr;
+  return INADDR_NONE;
+}
+weak_alias (__inet_addr, inet_addr)
diff --git a/resolv/res_init.c b/resolv/res_init.c
index 58c563898e..265e3cc6e3 100644
--- a/resolv/res_init.c
+++ b/resolv/res_init.c
@@ -399,8 +399,16 @@ res_vinit_1 (FILE *fp, struct resolv_conf_parser *parser)
               cp = parser->buffer + sizeof ("nameserver") - 1;
               while (*cp == ' ' || *cp == '\t')
                 cp++;
+
+              /* Ignore trailing contents on the name server line.  */
+              {
+                char *el;
+                if ((el = strpbrk (cp, " \t\n")) != NULL)
+                  *el = '\0';
+              }
+
               struct sockaddr *sa;
-              if ((*cp != '\0') && (*cp != '\n') && __inet_aton (cp, &a))
+              if ((*cp != '\0') && (*cp != '\n') && __inet_aton_exact (cp, &a))
                 {
                   sa = allocate_address_v4 (a, NAMESERVER_PORT);
                   if (sa == NULL)
@@ -410,9 +418,6 @@ res_vinit_1 (FILE *fp, struct resolv_conf_parser *parser)
                 {
                   struct in6_addr a6;
                   char *el;
-
-                  if ((el = strpbrk (cp, " \t\n")) != NULL)
-                    *el = '\0';
                   if ((el = strchr (cp, SCOPE_DELIMITER)) != NULL)
                     *el = '\0';
                   if ((*cp != '\0') && (__inet_pton (AF_INET6, cp, &a6) > 0))
@@ -472,7 +477,7 @@ res_vinit_1 (FILE *fp, struct resolv_conf_parser *parser)
                   char separator = *cp;
                   *cp = 0;
                   struct resolv_sortlist_entry e;
-                  if (__inet_aton (net, &a))
+                  if (__inet_aton_exact (net, &a))
                     {
                       e.addr = a;
                       if (is_sort_mask (separator))
@@ -484,7 +489,7 @@ res_vinit_1 (FILE *fp, struct resolv_conf_parser *parser)
                             cp++;
                           separator = *cp;
                           *cp = 0;
-                          if (__inet_aton (net, &a))
+                          if (__inet_aton_exact (net, &a))
                             e.mask = a.s_addr;
                           else
                             e.mask = net_mask (e.addr);
diff --git a/resolv/tst-aton.c b/resolv/tst-aton.c
index 08110a007a..eb734d7758 100644
--- a/resolv/tst-aton.c
+++ b/resolv/tst-aton.c
@@ -1,11 +1,29 @@
+/* Test legacy IPv4 text-to-address function inet_aton.
+   Copyright (C) 1998-2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <array_length.h>
 #include <stdio.h>
 #include <stdint.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 
-
-static struct tests
+static const struct tests
 {
   const char *input;
   int valid;
@@ -16,6 +34,7 @@ static struct tests
   { "-1", 0, 0 },
   { "256", 1, 0x00000100 },
   { "256.", 0, 0 },
+  { "255a", 0, 0 },
   { "256a", 0, 0 },
   { "0x100", 1, 0x00000100 },
   { "0200.0x123456", 1, 0x80123456 },
@@ -40,7 +59,12 @@ static struct tests
   { "1.2.256.4", 0, 0 },
   { "1.2.3.0x100", 0, 0 },
   { "323543357756889", 0, 0 },
-  { "10.1.2.3.4", 0, 0},
+  { "10.1.2.3.4", 0, 0 },
+  { "192.0.2.1", 1, 0xc0000201 },
+  { "192.0.2.2\nX", 1, 0xc0000202 },
+  { "192.0.2.3 Y", 1, 0xc0000203 },
+  { "192.0.2.3Z", 0, 0 },
+  { "192.000.002.010", 1, 0xc0000208 },
 };
 
 
@@ -50,7 +74,7 @@ do_test (void)
   int result = 0;
   size_t cnt;
 
-  for (cnt = 0; cnt < sizeof (tests) / sizeof (tests[0]); ++cnt)
+  for (cnt = 0; cnt < array_length (tests); ++cnt)
     {
       struct in_addr addr;
 
@@ -73,5 +97,4 @@ do_test (void)
   return result;
 }
 
-#define TEST_FUNCTION do_test ()
-#include "../test-skeleton.c"
+#include <support/test-driver.c>
diff --git a/resolv/tst-inet_aton_exact.c b/resolv/tst-inet_aton_exact.c
new file mode 100644
index 0000000000..0fdfa3d6aa
--- /dev/null
+++ b/resolv/tst-inet_aton_exact.c
@@ -0,0 +1,47 @@
+/* Test internal legacy IPv4 text-to-address function __inet_aton_exact.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <arpa/inet.h>
+#include <support/check.h>
+
+static int
+do_test (void)
+{
+  struct in_addr addr = { };
+
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.1", &addr), 1);
+  TEST_COMPARE (ntohl (addr.s_addr), 0xC0000201);
+
+  TEST_COMPARE (__inet_aton_exact ("192.000.002.010", &addr), 1);
+  TEST_COMPARE (ntohl (addr.s_addr), 0xC0000208);
+  TEST_COMPARE (__inet_aton_exact ("0xC0000234", &addr), 1);
+  TEST_COMPARE (ntohl (addr.s_addr), 0xC0000234);
+
+  /* Trailing content is not accepted.  */
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.2X", &addr), 0);
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.3 Y", &addr), 0);
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.4\nZ", &addr), 0);
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.5\tT", &addr), 0);
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.6 Y", &addr), 0);
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.7\n", &addr), 0);
+  TEST_COMPARE (__inet_aton_exact ("192.0.2.8\t", &addr), 0);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/resolv/tst-resolv-nondecimal.c b/resolv/tst-resolv-nondecimal.c
new file mode 100644
index 0000000000..a0df6f332a
--- /dev/null
+++ b/resolv/tst-resolv-nondecimal.c
@@ -0,0 +1,139 @@
+/* Test name resolution behavior for octal, hexadecimal IPv4 addresses.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <netdb.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/check_nss.h>
+#include <support/resolv_test.h>
+#include <support/support.h>
+
+static void
+response (const struct resolv_response_context *ctx,
+          struct resolv_response_builder *b,
+          const char *qname, uint16_t qclass, uint16_t qtype)
+{
+  /* The tests are not supposed send any DNS queries.  */
+  FAIL_EXIT1 ("unexpected DNS query for %s/%d/%d", qname, qclass, qtype);
+}
+
+static void
+run_query_addrinfo (const char *query, const char *address)
+{
+  char *quoted_query = support_quote_string (query);
+
+  struct addrinfo *ai;
+  struct addrinfo hints =
+    {
+     .ai_socktype = SOCK_STREAM,
+     .ai_protocol = IPPROTO_TCP,
+    };
+
+  char *context = xasprintf ("getaddrinfo \"%s\" AF_INET", quoted_query);
+  char *expected = xasprintf ("address: STREAM/TCP %s 80\n", address);
+  hints.ai_family = AF_INET;
+  int ret = getaddrinfo (query, "80", &hints, &ai);
+  check_addrinfo (context, ai, ret, expected);
+  if (ret == 0)
+    freeaddrinfo (ai);
+  free (context);
+
+  context = xasprintf ("getaddrinfo \"%s\" AF_UNSPEC", quoted_query);
+  hints.ai_family = AF_UNSPEC;
+  ret = getaddrinfo (query, "80", &hints, &ai);
+  check_addrinfo (context, ai, ret, expected);
+  if (ret == 0)
+    freeaddrinfo (ai);
+  free (expected);
+  free (context);
+
+  context = xasprintf ("getaddrinfo \"%s\" AF_INET6", quoted_query);
+  expected = xasprintf ("flags: AI_V4MAPPED\n"
+                        "address: STREAM/TCP ::ffff:%s 80\n",
+                        address);
+  hints.ai_family = AF_INET6;
+  hints.ai_flags = AI_V4MAPPED;
+  ret = getaddrinfo (query, "80", &hints, &ai);
+  check_addrinfo (context, ai, ret, expected);
+  if (ret == 0)
+    freeaddrinfo (ai);
+  free (expected);
+  free (context);
+
+  free (quoted_query);
+}
+
+static void
+run_query (const char *query, const char *address)
+{
+  char *quoted_query = support_quote_string (query);
+  char *context = xasprintf ("gethostbyname (\"%s\")", quoted_query);
+  char *expected = xasprintf ("name: %s\n"
+                              "address: %s\n", query, address);
+  check_hostent (context, gethostbyname (query), expected);
+  free (context);
+
+  context = xasprintf ("gethostbyname_r \"%s\"", quoted_query);
+  struct hostent storage;
+  char buf[4096];
+  struct hostent *e = NULL;
+  TEST_COMPARE (gethostbyname_r (query, &storage, buf, sizeof (buf),
+                                 &e, &h_errno), 0);
+  check_hostent (context, e, expected);
+  free (context);
+
+  context = xasprintf ("gethostbyname2 (\"%s\", AF_INET)", quoted_query);
+  check_hostent (context, gethostbyname2 (query, AF_INET), expected);
+  free (context);
+
+  context = xasprintf ("gethostbyname2_r \"%s\" AF_INET", quoted_query);
+  e = NULL;
+  TEST_COMPARE (gethostbyname2_r (query, AF_INET, &storage, buf, sizeof (buf),
+                                  &e, &h_errno), 0);
+  check_hostent (context, e, expected);
+  free (context);
+  free (expected);
+
+  free (quoted_query);
+
+  /* The gethostbyname tests are always valid for getaddrinfo, but not
+     vice versa.  */
+  run_query_addrinfo (query, address);
+}
+
+static int
+do_test (void)
+{
+  struct resolv_test *aux = resolv_test_start
+    ((struct resolv_redirect_config)
+     {
+       .response_callback = response,
+     });
+
+  run_query ("192.000.002.010", "192.0.2.8");
+
+  /* Hexadecimal numbers are not accepted by gethostbyname.  */
+  run_query_addrinfo ("0xc0000210", "192.0.2.16");
+  run_query_addrinfo ("192.0x234", "192.0.2.52");
+
+  resolv_test_end (aux);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/resolv/tst-resolv-trailing.c b/resolv/tst-resolv-trailing.c
new file mode 100644
index 0000000000..7504bdae57
--- /dev/null
+++ b/resolv/tst-resolv-trailing.c
@@ -0,0 +1,136 @@
+/* Test name resolution behavior with trailing characters.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <array_length.h>
+#include <netdb.h>
+#include <support/check.h>
+#include <support/check_nss.h>
+#include <support/resolv_test.h>
+#include <support/support.h>
+
+static void
+response (const struct resolv_response_context *ctx,
+          struct resolv_response_builder *b,
+          const char *qname, uint16_t qclass, uint16_t qtype)
+{
+  /* The tests are not supposed send any DNS queries.  */
+  FAIL_EXIT1 ("unexpected DNS query for %s/%d/%d", qname, qclass, qtype);
+}
+
+static int
+do_test (void)
+{
+  struct resolv_test *aux = resolv_test_start
+    ((struct resolv_redirect_config)
+     {
+       .response_callback = response,
+     });
+
+  static const char *const queries[] =
+    {
+     "192.0.2.1 ",
+     "192.0.2.2\t",
+     "192.0.2.3\n",
+     "192.0.2.4 X",
+     "192.0.2.5\tY",
+     "192.0.2.6\nZ",
+     "192.0.2. ",
+     "192.0.2.\t",
+     "192.0.2.\n",
+     "192.0.2. X",
+     "192.0.2.\tY",
+     "192.0.2.\nZ",
+     "2001:db8::1 ",
+     "2001:db8::2\t",
+     "2001:db8::3\n",
+     "2001:db8::4 X",
+     "2001:db8::5\tY",
+     "2001:db8::6\nZ",
+    };
+  for (size_t query_idx = 0; query_idx < array_length (queries); ++query_idx)
+    {
+      const char *query = queries[query_idx];
+      struct hostent storage;
+      char buf[4096];
+      struct hostent *e;
+
+      h_errno = 0;
+      TEST_VERIFY (gethostbyname (query) == NULL);
+      TEST_COMPARE (h_errno, HOST_NOT_FOUND);
+
+      h_errno = 0;
+      e = NULL;
+      TEST_COMPARE (gethostbyname_r (query, &storage, buf, sizeof (buf),
+                                     &e, &h_errno), 0);
+      TEST_VERIFY (e == NULL);
+      TEST_COMPARE (h_errno, HOST_NOT_FOUND);
+
+      h_errno = 0;
+      TEST_VERIFY (gethostbyname2 (query, AF_INET) == NULL);
+      TEST_COMPARE (h_errno, HOST_NOT_FOUND);
+
+      h_errno = 0;
+      e = NULL;
+      TEST_COMPARE (gethostbyname2_r (query, AF_INET,
+                                      &storage, buf, sizeof (buf),
+                                     &e, &h_errno), 0);
+      TEST_VERIFY (e == NULL);
+      TEST_COMPARE (h_errno, HOST_NOT_FOUND);
+
+      h_errno = 0;
+      TEST_VERIFY (gethostbyname2 (query, AF_INET6) == NULL);
+      TEST_COMPARE (h_errno, HOST_NOT_FOUND);
+
+      h_errno = 0;
+      e = NULL;
+      TEST_COMPARE (gethostbyname2_r (query, AF_INET6,
+                                      &storage, buf, sizeof (buf),
+                                     &e, &h_errno), 0);
+      TEST_VERIFY (e == NULL);
+      TEST_COMPARE (h_errno, HOST_NOT_FOUND);
+
+      static const int gai_flags[] =
+        {
+         0,
+         AI_ADDRCONFIG,
+         AI_NUMERICHOST,
+         AI_IDN,
+         AI_IDN | AI_NUMERICHOST,
+         AI_V4MAPPED,
+         AI_V4MAPPED | AI_NUMERICHOST,
+        };
+      for (size_t gai_flags_idx; gai_flags_idx < array_length (gai_flags);
+             ++gai_flags_idx)
+        {
+          struct addrinfo hints = { .ai_flags = gai_flags[gai_flags_idx], };
+          struct addrinfo *ai;
+          hints.ai_family = AF_INET;
+          TEST_COMPARE (getaddrinfo (query, "80", &hints, &ai), EAI_NONAME);
+          hints.ai_family = AF_INET6;
+          TEST_COMPARE (getaddrinfo (query, "80", &hints, &ai), EAI_NONAME);
+          hints.ai_family = AF_UNSPEC;
+          TEST_COMPARE (getaddrinfo (query, "80", &hints, &ai), EAI_NONAME);
+        }
+    };
+
+  resolv_test_end (aux);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/posix/getaddrinfo.c b/sysdeps/posix/getaddrinfo.c
index aa69eb7e54..aa054b620f 100644
--- a/sysdeps/posix/getaddrinfo.c
+++ b/sysdeps/posix/getaddrinfo.c
@@ -488,7 +488,7 @@ gaih_inet (const char *name, const struct gaih_service *service,
 	  malloc_name = true;
 	}
 
-      if (__inet_aton (name, (struct in_addr *) at->addr) != 0)
+      if (__inet_aton_exact (name, (struct in_addr *) at->addr) != 0)
 	{
 	  if (req->ai_family == AF_UNSPEC || req->ai_family == AF_INET)
 	    at->family = AF_INET;