[glibc] nscd: Drop local address tuple variable [BZ #29607]

[Siddhesh Poyarekar <siddhesh@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=6e33e5c4b73cea7b8aa3de0947123db16200fb65

commit 6e33e5c4b73cea7b8aa3de0947123db16200fb65
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date:   Tue Oct 4 18:40:25 2022 -0400

    nscd: Drop local address tuple variable [BZ #29607]
    
    When a request needs to be resent (e.g. due to insufficient buffer
    space), the references to subsequent tuples in the local variable are
    stale and should not be used.  This used to work by accident before, but
    since 1d495912a it no longer does.  Instead of trying to reset it, just
    let gethostbyname4_r write into TUMPBUF6 for us, thus maintaining a
    consistent state at all times.  This is now consistent with what is done
    in gaih_inet for getaddrinfo.
    
    Resolves: BZ #29607
    Reported-by: Holger Hoffstätte <holger@applied-asynchrony.com>
    Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
    Reviewed-by: Carlos O'Donell <carlos@redhat.com>

Diff:
---
 nscd/aicache.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/nscd/aicache.c b/nscd/aicache.c
index 51e793199f..e0baed170b 100644
--- a/nscd/aicache.c
+++ b/nscd/aicache.c
@@ -110,11 +110,10 @@ addhstaiX (struct database_dyn *db, int fd, request_header *req,
 							  "gethostbyname4_r");
       if (fct4 != NULL)
 	{
-	  struct gaih_addrtuple atmem;
 	  struct gaih_addrtuple *at;
 	  while (1)
 	    {
-	      at = &atmem;
+	      at = NULL;
 	      rc6 = 0;
 	      herrno = 0;
 	      status[1] = DL_CALL_FCT (fct4, (key, &at,
@@ -137,7 +136,7 @@ addhstaiX (struct database_dyn *db, int fd, request_header *req,
 	    goto next_nip;
 
 	  /* We found the data.  Count the addresses and the size.  */
-	  for (const struct gaih_addrtuple *at2 = at = &atmem; at2 != NULL;
+	  for (const struct gaih_addrtuple *at2 = at; at2 != NULL;
 	       at2 = at2->next)
 	    {
 	      ++naddrs;