Handle dynamic definition of SIGSTKSZ as of glibc 2.34 on Linux.

ok bluhm@, inoguchi@, tb@, deraadt@

1 files changed, 24 insertions, 7 deletions

diff --git a/src/regress/lib/libc/explicit_bzero/explicit_bzero.c b/src/regress/lib/libc/explicit_bzero/explicit_bzero.c
index 34c60baa8a..9c0e917829 100644
--- a/src/regress/lib/libc/explicit_bzero/explicit_bzero.c
+++ b/src/regress/lib/libc/explicit_bzero/explicit_bzero.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: explicit_bzero.c,v 1.6 2014/07/11 01:10:35 matthew Exp $      */
+/*      $OpenBSD: explicit_bzero.c,v 1.7 2021/03/27 11:17:58 bcook Exp $        */
 /*
  * Copyright (c) 2014 Google Inc.
  *
@@ -18,6 +18,7 @@
 #include <assert.h>
 #include <errno.h>
 #include <signal.h>
+#include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
@@ -36,20 +37,34 @@ enum {
         SECRETBYTES = SECRETCOUNT * sizeof(secret)
 };
 
-static char altstack[SIGSTKSZ + SECRETBYTES];
+/*
+ * As of glibc 2.34, when _GNU_SOURCE is defined, SIGSTKSZ is no longer
+ * constant on Linux. SIGSTKSZ is redefined to sysconf (_SC_SIGSTKSZ).
+ */
+static char *altstack;
+#define ALTSTACK_SIZE (SIGSTKSZ + SECRETBYTES)
 
 static void
 setup_stack(void)
 {
+        altstack = calloc(1, ALTSTACK_SIZE);
+        ASSERT_NE(NULL, altstack);
+
         const stack_t sigstk = {
                 .ss_sp = altstack,
-                .ss_size = sizeof(altstack),
+                .ss_size = ALTSTACK_SIZE
         };
 
         ASSERT_EQ(0, sigaltstack(&sigstk, NULL));
 }
 
 static void
+cleanup_stack(void)
+{
+        free(altstack);
+}
+
+static void
 assert_on_stack(void)
 {
         stack_t cursigstk;
@@ -129,7 +144,7 @@ test_without_bzero()
         char buf[SECRETBYTES];
         assert_on_stack();
         populate_secret(buf, sizeof(buf));
-        char *res = memmem(altstack, sizeof(altstack), buf, sizeof(buf));
+        char *res = memmem(altstack, ALTSTACK_SIZE, buf, sizeof(buf));
         ASSERT_NE(NULL, res);
         return (res);
 }
@@ -140,7 +155,7 @@ test_with_bzero()
         char buf[SECRETBYTES];
         assert_on_stack();
         populate_secret(buf, sizeof(buf));
-        char *res = memmem(altstack, sizeof(altstack), buf, sizeof(buf));
+        char *res = memmem(altstack, ALTSTACK_SIZE, buf, sizeof(buf));
         ASSERT_NE(NULL, res);
         explicit_bzero(buf, sizeof(buf));
         return (res);
@@ -183,15 +198,17 @@ main()
          * on the stack.  This sanity checks that call_on_stack() and
          * populate_secret() work as intended.
          */
-        memset(altstack, 0, sizeof(altstack));
+        memset(altstack, 0, ALTSTACK_SIZE);
         call_on_stack(do_test_without_bzero);
 
         /*
          * Now test with a call to explicit_bzero() and check that we
          * *don't* find any instances of the secret data.
          */
-        memset(altstack, 0, sizeof(altstack));
+        memset(altstack, 0, ALTSTACK_SIZE);
         call_on_stack(do_test_with_bzero);
 
+        cleanup_stack();
+
         return (0);
 }