Upstream commit, fixing [BZ #15218]:

commit b957ced8890a4438c8efe2c15e5abf4e327f25cf

Author: Andreas Schwab <schwab@suse.de>

Date:   Tue Oct 15 10:21:13 2013 +0200

    Don't use gethostbyaddr to determine canonical name

--- glibc-2.17-c758a686/sysdeps/posix/getaddrinfo.c

+++ glibc-2.17-c758a686/sysdeps/posix/getaddrinfo.c

@@ -565,8 +565,8 @@ gaih_inet (const char *name, const struct gaih_service *service,

 	  /* If we do not have to look for IPv6 addresses, use

 	     the simple, old functions, which do not support

-	     IPv6 scope ids. */

-	  if (req->ai_family == AF_INET)

+	     IPv6 scope ids, nor retrieving the canonical name.  */

+	  if (req->ai_family == AF_INET && (req->ai_flags & AI_CANONNAME) == 0)

 	    {

 	      /* Allocate additional room for struct host_data.  */

 	      size_t tmpbuflen = (512 + MAX_NR_ALIASES * sizeof(char*)

@@ -1107,70 +1107,10 @@ gaih_inet (const char *name, const struct gaih_service *service,

 	/* Only the first entry gets the canonical name.  */

 	if (at2 == at && (req->ai_flags & AI_CANONNAME) != 0)

 	  {

-	    char *tmpbuf2 = NULL;

-	    bool malloc_tmpbuf2 = false;

-

 	    if (canon == NULL)

-	      {

-		struct hostent *h = NULL;

-		int herrno;

-		struct hostent th;

-		/* Add room for struct host_data.  */

-		size_t tmpbuf2len = (512 + (MAX_NR_ALIASES+MAX_NR_ADDRS+1)

-				     * sizeof(char*) + 16 * sizeof(char));

-

-		do

-		  {

-		    if (__libc_use_alloca (alloca_used + 2 * tmpbuf2len))

-		      tmpbuf2 = extend_alloca_account (tmpbuf2, tmpbuf2len,

-						       tmpbuf2len * 2,

-						       alloca_used);

-		    else

-		      {

-			char *newp = realloc (malloc_tmpbuf2 ? tmpbuf2 : NULL,

-					      2 * tmpbuf2len);

-			if (newp == NULL)

-			  {

-			    if (malloc_tmpbuf2)

-			      free (tmpbuf2);

-			    result = -EAI_MEMORY;

-			    goto free_and_return;

-			  }

-

-			tmpbuf2 = newp;

-			tmpbuf2len = 2 * tmpbuf2len;

-			malloc_tmpbuf2 = true;

-		      }

-

-		    rc = __gethostbyaddr_r (at2->addr,

-					    ((at2->family == AF_INET6)

-					     ? sizeof (struct in6_addr)

-					     : sizeof (struct in_addr)),

-					    at2->family, &th, tmpbuf2,

-					    tmpbuf2len, &h, &herrno);

-		  }

-		while (rc == ERANGE && herrno == NETDB_INTERNAL);

-

-		if (rc != 0 && herrno == NETDB_INTERNAL)

-		  {

-		    if (malloc_tmpbuf2)

-		      free (tmpbuf2);

-

-		    __set_h_errno (herrno);

-		    result = -EAI_SYSTEM;

-		    goto free_and_return;

-		  }

-

-		if (h != NULL)

-		  canon = h->h_name;

-		else

-		  {

-		    assert (orig_name != NULL);

-		    /* If the canonical name cannot be determined, use

-		       the passed in string.  */

-		    canon = orig_name;

-		  }

-	      }

+	      /* If the canonical name cannot be determined, use

+		 the passed in string.  */

+	      canon = orig_name;

 #ifdef HAVE_LIBIDN

 	    if (req->ai_flags & AI_CANONIDN)

@@ -1185,9 +1125,6 @@ gaih_inet (const char *name, const struct gaih_service *service,

 		int rc = __idna_to_unicode_lzlz (canon, &out, idn_flags);

 		if (rc != IDNA_SUCCESS)

 		  {

-		    if (malloc_tmpbuf2)

-		      free (tmpbuf2);

-

 		    if (rc == IDNA_MALLOC_ERROR)

 		      result = -EAI_MEMORY;

 		    else if (rc == IDNA_DLOPEN_ERROR)

@@ -1217,17 +1154,11 @@ gaih_inet (const char *name, const struct gaih_service *service,

 		    canon = strdup (canon);

 		    if (canon == NULL)

 		      {

-			if (malloc_tmpbuf2)

-			  free (tmpbuf2);

-

 			result = -EAI_MEMORY;

 			goto free_and_return;

 		      }

 		  }

 	      }

-

-	    if (malloc_tmpbuf2)

-	      free (tmpbuf2);

 	  }

 	family = at2->family;