nptl: Preserve error in setxid thread broadcast in coredumps [BZ #22153]

ChangeLog

@@ -1,3 +1,9 @@
+2017-10-13  Peter Zelezny  <peter.zelezny@dektech.com.au>
+
+	[BZ #22153]
+	* nptl/allocatestack.c (__nptl_setxid_error): Preserve error code
+	in coredumps.
+
 2017-10-13  James Clarke  <jrtc27@jrtc27.com>
 
 	* sysdeps/powerpc/powerpc32/dl-machine.h (elf_machine_rela):

nptl/allocatestack.c

@@ -1105,8 +1105,13 @@ __nptl_setxid_error (struct xid_command *cmdp, int error)
       if (olderror == error)
 	break;
       if (olderror != -1)
-	/* Mismatch between current and previous results.  */
-	abort ();
+	{
+	  /* Mismatch between current and previous results.  Save the
+	     error value to memory so that is not clobbered by the
+	     abort function and preserved in coredumps.  */
+	  volatile int xid_err __attribute__((unused)) = error;
+	  abort ();
+	}
     }
   while (atomic_compare_and_exchange_bool_acq (&cmdp->error, error, -1));
 }