https://sourceware.org/ml/libc-alpha/2014-04/msg00008.html

Index: eglibc-2.19/stdlib/tst-setcontext.c
===================================================================
--- eglibc-2.19.orig/stdlib/tst-setcontext.c	2014-01-03 17:51:28.000000000 +0000
+++ eglibc-2.19/stdlib/tst-setcontext.c	2150-05-10 06:54:54.405789000 +0000
@@ -16,6 +16,7 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <errno.h>
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -144,6 +145,9 @@
   atexit (check_called);
 
   char st1[32768];
+  stack_t stack_before, stack_after;
+
+  sigaltstack(NULL, &stack_before);
 
   puts ("making contexts");
   if (getcontext (&ctx[1]) != 0)
@@ -207,6 +211,8 @@
   puts ("back at main program");
   back_in_main = 1;
 
+  sigaltstack(NULL, &stack_after);
+
   if (was_in_f1 == 0)
     {
       puts ("didn't reach f1");
@@ -218,6 +224,21 @@
       exit (1);
     }
 
+  /* Check sigaltstack state is not clobbered as in BZ #16629.  */
+  if (stack_before.ss_sp != stack_after.ss_sp)
+    {
+      printf ("stack ss_sp mismatch: %p %p\n",
+	      stack_before.ss_sp, stack_after.ss_sp);
+      exit (1);
+    }
+
+  if (stack_before.ss_size != stack_after.ss_size)
+    {
+      printf ("stack ss_size mismatch: %zd %zd\n",
+	      stack_before.ss_size, stack_after.ss_size);
+      exit (1);
+    }
+
   puts ("test succeeded");
   return 0;
 }