[2.26 COMMITTED] Fix crash in resolver on memory allocation failure (bug 23005)

[Florian Weimer]

From: Andreas Schwab <schwab@suse.de>

(cherry picked from commit f178e59fa5eefbbd37fde040ae8334aa5c857ee1)

2018-03-27  Andreas Schwab  <schwab@suse.de>

	[BZ #23005]
	* resolv/res_send.c (__res_context_send): Return ENOMEM if
	allocation of private copy of nsaddr_list fails.

diff --git a/NEWS b/NEWS
index dcbb2b0ff6..4d360a426e 100644
--- a/NEWS
+++ b/NEWS
@@ -118,6 +118,7 @@ The following bugs are resolved with this release:
   [22685] powerpc: Fix syscalls during early process initialization
   [22715] x86-64: Properly align La_x86_64_retval to VEC_SIZE
   [22774] malloc: Integer overflow in malloc (CVE-2018-6551)
+  [23005] resolv: Fix crash in resolver on memory allocation failure
   [23024] getlogin_r: return early when linux sentinel value is set
   [23037] resolv: Fully initialize struct mmsghdr in send_dg
 
diff --git a/resolv/res_send.c b/resolv/res_send.c
index 0ca02f9843..83f35f60da 100644
--- a/resolv/res_send.c
+++ b/resolv/res_send.c
@@ -471,6 +471,11 @@ __res_context_send (struct resolv_context *ctx,
 					'\0',
 					sizeof (struct sockaddr_in6)
 					- sizeof (struct sockaddr_in));
+			else
+			  {
+			    __set_errno (ENOMEM);
+			    return -1;
+			  }
 		}
 		EXT(statp).nscount = statp->nscount;
 	}