[glibc/release/2.38/master] Fix leak in getaddrinfo introduced by the fix for CVE-2023-4806 [BZ #30843]

[Siddhesh Poyarekar <siddhesh@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=5ee59ca371b99984232d7584fe2b1a758b4421d3

commit 5ee59ca371b99984232d7584fe2b1a758b4421d3
Author: Romain Geissler <romain.geissler@amadeus.com>
Date:   Mon Sep 25 01:21:51 2023 +0100

    Fix leak in getaddrinfo introduced by the fix for CVE-2023-4806 [BZ #30843]
    
    This patch fixes a very recently added leak in getaddrinfo.
    
    This was assigned CVE-2023-5156.
    
    Resolves: BZ #30884
    Related: BZ #30842
    
    Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
    (cherry picked from commit ec6b95c3303c700eb89eebeda2d7264cc184a796)

Diff:
---
 nss/Makefile                    | 20 ++++++++++++++++++++
 nss/tst-nss-gai-hv2-canonname.c |  3 +++
 sysdeps/posix/getaddrinfo.c     |  4 +---
 3 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/nss/Makefile b/nss/Makefile
index 8a5126ecf3..668ba34b18 100644
--- a/nss/Makefile
+++ b/nss/Makefile
@@ -149,6 +149,15 @@ endif
 extra-test-objs		+= nss_test1.os nss_test2.os nss_test_errno.os \
 			   nss_test_gai_hv2_canonname.os
 
+ifeq ($(run-built-tests),yes)
+ifneq (no,$(PERL))
+tests-special += $(objpfx)mtrace-tst-nss-gai-hv2-canonname.out
+endif
+endif
+
+generated += mtrace-tst-nss-gai-hv2-canonname.out \
+		tst-nss-gai-hv2-canonname.mtrace
+
 include ../Rules
 
 ifeq (yes,$(have-selinux))
@@ -217,6 +226,17 @@ endif
 $(objpfx)tst-nss-files-alias-leak.out: $(objpfx)/libnss_files.so
 $(objpfx)tst-nss-files-alias-truncated.out: $(objpfx)/libnss_files.so
 
+tst-nss-gai-hv2-canonname-ENV = \
+		MALLOC_TRACE=$(objpfx)tst-nss-gai-hv2-canonname.mtrace \
+		LD_PRELOAD=$(common-objpfx)/malloc/libc_malloc_debug.so
+$(objpfx)mtrace-tst-nss-gai-hv2-canonname.out: \
+  $(objpfx)tst-nss-gai-hv2-canonname.out
+	{ test -r $(objpfx)tst-nss-gai-hv2-canonname.mtrace \
+	|| ( echo "tst-nss-gai-hv2-canonname.mtrace does not exist"; exit 77; ) \
+	&& $(common-objpfx)malloc/mtrace \
+	$(objpfx)tst-nss-gai-hv2-canonname.mtrace; } > $@; \
+	$(evaluate-test)
+
 # Disable DT_RUNPATH on NSS tests so that the glibc internal NSS
 # functions can load testing NSS modules via DT_RPATH.
 LDFLAGS-tst-nss-test1 = -Wl,--disable-new-dtags
diff --git a/nss/tst-nss-gai-hv2-canonname.c b/nss/tst-nss-gai-hv2-canonname.c
index d5f10c07d6..7db53cf09d 100644
--- a/nss/tst-nss-gai-hv2-canonname.c
+++ b/nss/tst-nss-gai-hv2-canonname.c
@@ -21,6 +21,7 @@
 #include <netdb.h>
 #include <stdlib.h>
 #include <string.h>
+#include <mcheck.h>
 #include <support/check.h>
 #include <support/xstdio.h>
 #include "nss/tst-nss-gai-hv2-canonname.h"
@@ -41,6 +42,8 @@ static void do_prepare (int a, char **av)
 static int
 do_test (void)
 {
+  mtrace ();
+
   __nss_configure_lookup ("hosts", "test_gai_hv2_canonname");
 
   struct addrinfo hints = {};
diff --git a/sysdeps/posix/getaddrinfo.c b/sysdeps/posix/getaddrinfo.c
index b2236b105c..13082305d3 100644
--- a/sysdeps/posix/getaddrinfo.c
+++ b/sysdeps/posix/getaddrinfo.c
@@ -1196,9 +1196,7 @@ free_and_return:
   if (malloc_name)
     free ((char *) name);
   free (addrmem);
-  if (res.free_at)
-    free (res.at);
-  free (res.canon);
+  gaih_result_reset (&res);
 
   return result;
 }