glibc: fix Segmentation fault in gethostid.c

Linux gethostid: Check for NULL value from gethostbyname_r [BZ #23679]

A NULL value can happen with certain gethostbyname_r failures.

Before this patch, there is a Segmentation fault
as below:
 # /mybuild/hostid
 Segmentation fault
 # gdb /mybuild/hostid
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 Reading symbols from /mybuild/hostid...done.
 (gdb) r
 Starting program: /mybuild/hostid

 Program received signal SIGSEGV, Segmentation fault.
 0x00007ffff7f0330e in gethostid () at ../sysdeps/unix/sysv/linux/gethostid.c:125
 125	  memcpy (&in, hp->h_addr,
 (gdb) bt
 #0  0x00007ffff7f0330e in gethostid () at ../sysdeps/unix/sysv/linux/gethostid.c:125
 #1  0x0000555555555159 in main ()

 # cat /mybuild/hostid.c
 #include <stdio.h>
 #include <unistd.h>

 int
 main(int argc, char *argv[])
 {
    long hostid;
    hostid = gethostid();
    printf("the hostid is %ld\n", hostid);

 }

(From OE-Core rev: 92c266fd9b1c4034a13bd5b102d1817df388a7b5)

Signed-off-by: Mingli Yu <Mingli.Yu@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/glibc/glibc/0001-Linux-gethostid-Check-for-NULL-value-from-gethostbyn.patch

@@ -0,0 +1,38 @@
+From e7d22db29cfdd2f1fb97a70a76fa53d151569945 Mon Sep 17 00:00:00 2001
+From: Mingli Yu <Mingli.Yu@windriver.com>
+Date: Thu, 20 Sep 2018 12:41:13 +0200
+Subject: [PATCH] Linux gethostid: Check for NULL value from gethostbyname_r [BZ #23679]
+
+A NULL value can happen with certain gethostbyname_r failures.
+
+(cherry picked from commit 1214ba06e6771acb953a190091b0f6055c64fd25)
+
+Upstream-Status: Backport [https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=1214ba06e6771acb953a190091b0f6055c64fd25]
+
+Signed-off-by: Mingli Yu <mingli.yu@windriver.com>
+---
+ sysdeps/unix/sysv/linux/gethostid.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/sysdeps/unix/sysv/linux/gethostid.c b/sysdeps/unix/sysv/linux/gethostid.c
+index 2e20f034dc..ee0190e7f9 100644
+--- a/sysdeps/unix/sysv/linux/gethostid.c
++++ b/sysdeps/unix/sysv/linux/gethostid.c
+@@ -102,12 +102,12 @@ gethostid (void)
+     {
+       int ret = __gethostbyname_r (hostname, &hostbuf,
+ 				   tmpbuf.data, tmpbuf.length, &hp, &herr);
+-      if (ret == 0)
++      if (ret == 0 && hp != NULL)
+ 	break;
+       else
+ 	{
+ 	  /* Enlarge the buffer on ERANGE.  */
+-	  if (herr == NETDB_INTERNAL && errno == ERANGE)
++	  if (ret != 0 && herr == NETDB_INTERNAL && errno == ERANGE)
+ 	    {
+ 	      if (!scratch_buffer_grow (&tmpbuf))
+ 		return 0;
+-- 
+2.17.1
+

meta/recipes-core/glibc/glibc_2.28.bb

@@ -47,6 +47,7 @@ SRC_URI = "${GLIBC_GIT_URI};branch=${SRCBRANCH};name=glibc \
            file://0030-intl-Emit-no-lines-in-bison-generated-files.patch \
            file://0031-sysdeps-ieee754-prevent-maybe-uninitialized-errors.patch \
            file://0032-soft-fp-ignore-maybe-uninitialized.patch \
+           file://0001-Linux-gethostid-Check-for-NULL-value-from-gethostbyn.patch \
 "
 
 NATIVESDKFIXES ?= ""