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

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

diff --git a/regress/lib/libc/explicit_bzero/explicit_bzero.c b/regress/lib/libc/explicit_bzero/explicit_bzero.c
index 34c60ba..9c0e917 100644 (file)
--- a/regress/lib/libc/explicit_bzero/explicit_bzero.c
+++ b/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>
 
@@ -36,19 +37,33 @@ 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)
 {
@@ -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);
 }