commit 8a5df95ffa83f525a4f638ead743f4fa2b7fe45a
Author: Florian Weimer <fweimer@redhat.com>
Date: Thu Jan 4 18:00:05 2018 +0100
i386: In makecontext, align the stack before calling exit [BZ #22667]
Before this change, if glibc was compiled with SSE instructions and a
sufficiently recent GCC, an unaligned stack access in
__run_exit_handlers would cause stdlib/tst-makecontext to crash.
diff --git a/stdlib/Makefile b/stdlib/Makefile
index 764aad69d8c50b9b..b5553eafc2a4bbd5 100644
--- a/stdlib/Makefile
+++ b/stdlib/Makefile
@@ -71,7 +71,8 @@ tests := tst-strtol tst-strtod testmb testrand testsort testdiv \
tst-qsort2 tst-makecontext2 tst-strtod6 tst-unsetenv1 \
tst-makecontext3 bug-getcontext bug-fmtmsg1 \
tst-secure-getenv tst-strtod-overflow tst-strtod-round \
- tst-tininess tst-strtod-underflow tst-strfmon_l
+ tst-tininess tst-strtod-underflow tst-strfmon_l \
+ tst-makecontext-align
tests-static := tst-secure-getenv
include ../Makeconfig
diff --git a/stdlib/tst-makecontext-align.c b/stdlib/tst-makecontext-align.c
new file mode 100644
index 0000000000000000..82394b4f6b024c9b
--- /dev/null
+++ b/stdlib/tst-makecontext-align.c
@@ -0,0 +1,241 @@
+/* Check stack alignment provided by makecontext.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/namespace.h>
+#include <support/xunistd.h>
+#include <sys/mman.h>
+#include <ucontext.h>
+
+/* Used for error reporting. */
+static const char *context;
+
+/* Check that ADDRESS is aligned to ALIGNMENT bytes, behind a compiler
+ barrier. */
+__attribute__ ((noinline, noclone, weak))
+void
+check_align (void *address, size_t alignment)
+{
+ uintptr_t uaddress = (uintptr_t) address;
+ if ((uaddress % alignment) != 0)
+ {
+ support_record_failure ();
+ printf ("error: %s: object at address %p is not aligned to %zu bytes\n",
+ context, address, alignment);
+ }
+}
+
+/* Various alignment checking functions. */
+
+__attribute__ ((noinline, noclone, weak))
+void
+check_align_int (void)
+{
+ int a;
+ check_align (&a, __alignof__ (a));
+}
+
+__attribute__ ((noinline, noclone, weak))
+void
+check_align_long (void)
+{
+ long a;
+ check_align (&a, __alignof__ (a));
+}
+
+__attribute__ ((noinline, noclone, weak))
+void
+check_align_long_long (void)
+{
+ long long a;
+ check_align (&a, __alignof__ (a));
+}
+
+__attribute__ ((noinline, noclone, weak))
+void
+check_align_double (void)
+{
+ double a;
+ check_align (&a, __alignof__ (a));
+}
+
+__attribute__ ((noinline, noclone, weak))
+void
+check_align_4 (void)
+{
+ int a __attribute__ ((aligned (4)));
+ check_align (&a, 4);
+}
+
+__attribute__ ((noinline, noclone, weak))
+void
+check_align_8 (void)
+{
+ double a __attribute__ ((aligned (8)));
+ check_align (&a, 8);
+}
+
+__attribute__ ((noinline, noclone, weak))
+void
+check_align_16 (void)
+{
+ struct aligned
+ {
+ double x0 __attribute__ ((aligned (16)));
+ double x1;
+ } a;
+ check_align (&a, 16);
+}
+
+__attribute__ ((noinline, noclone, weak))
+void
+check_align_32 (void)
+{
+ struct aligned
+ {
+ double x0 __attribute__ ((aligned (32)));
+ double x1;
+ double x2;
+ double x3;
+ } a;
+ check_align (&a, 32);
+}
+
+/* Call all the alignment checking functions. */
+__attribute__ ((noinline, noclone, weak))
+void
+check_alignments (void)
+{
+ check_align_int ();
+ check_align_long ();
+ check_align_long_long ();
+ check_align_double ();
+ check_align_4 ();
+ check_align_8 ();
+ check_align_16 ();
+ check_align_32 ();
+}
+
+/* Callback functions for makecontext and their invokers (to be used
+ with support_isolate_in_subprocess). */
+
+static ucontext_t ucp;
+
+static void
+callback_0 (void)
+{
+ context = "callback_0";
+ check_alignments ();
+ context = "after return from callback_0";
+}
+
+static void
+invoke_callback_0 (void *closure)
+{
+ makecontext (&ucp, (void *) callback_0, 0);
+ if (setcontext (&ucp) != 0)
+ FAIL_EXIT1 ("setcontext");
+ FAIL_EXIT1 ("setcontext returned");
+}
+
+static void
+callback_1 (int arg1)
+{
+ context = "callback_1";
+ check_alignments ();
+ TEST_COMPARE (arg1, 101);
+ context = "after return from callback_1";
+}
+
+static void
+invoke_callback_1 (void *closure)
+{
+ makecontext (&ucp, (void *) callback_1, 1, 101);
+ if (setcontext (&ucp) != 0)
+ FAIL_EXIT1 ("setcontext");
+ FAIL_EXIT1 ("setcontext returned");
+}
+
+static void
+callback_2 (int arg1, int arg2)
+{
+ context = "callback_2";
+ check_alignments ();
+ TEST_COMPARE (arg1, 201);
+ TEST_COMPARE (arg2, 202);
+ context = "after return from callback_2";
+}
+
+static void
+invoke_callback_2 (void *closure)
+{
+ makecontext (&ucp, (void *) callback_2, 2, 201, 202);
+ if (setcontext (&ucp) != 0)
+ FAIL_EXIT1 ("setcontext");
+ FAIL_EXIT1 ("setcontext returned");
+}
+
+static void
+callback_3 (int arg1, int arg2, int arg3)
+{
+ context = "callback_3";
+ check_alignments ();
+ TEST_COMPARE (arg1, 301);
+ TEST_COMPARE (arg2, 302);
+ TEST_COMPARE (arg3, 303);
+ context = "after return from callback_3";
+}
+
+static void
+invoke_callback_3 (void *closure)
+{
+ makecontext (&ucp, (void *) callback_3, 3, 301, 302, 303);
+ if (setcontext (&ucp) != 0)
+ FAIL_EXIT1 ("setcontext");
+ FAIL_EXIT1 ("setcontext returned");
+}
+
+static int
+do_test (void)
+{
+ context = "direct call";
+ check_alignments ();
+
+ atexit (check_alignments);
+
+ if (getcontext (&ucp) != 0)
+ FAIL_UNSUPPORTED ("getcontext");
+
+ ucp.uc_link = NULL;
+ ucp.uc_stack.ss_size = 512 * 1024;
+ ucp.uc_stack.ss_sp = xmmap (NULL, ucp.uc_stack.ss_size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1);
+
+ support_isolate_in_subprocess (invoke_callback_0, NULL);
+ support_isolate_in_subprocess (invoke_callback_1, NULL);
+ support_isolate_in_subprocess (invoke_callback_2, NULL);
+ support_isolate_in_subprocess (invoke_callback_3, NULL);
+
+ return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/unix/sysv/linux/i386/makecontext.S b/sysdeps/unix/sysv/linux/i386/makecontext.S
index 48643864b05568b0..5e02aa78925c4bdc 100644
--- a/sysdeps/unix/sysv/linux/i386/makecontext.S
+++ b/sysdeps/unix/sysv/linux/i386/makecontext.S
@@ -113,9 +113,19 @@ L(exitcode):
call JUMPTARGET(__setcontext)
/* If this returns (which can happen if the syscall fails) we'll
exit the program with the return error value (-1). */
+ jmp L(call_exit)
- movl %eax, (%esp)
-2: call HIDDEN_JUMPTARGET(exit)
+2:
+ /* Exit with status 0. */
+ xorl %eax, %eax
+
+L(call_exit):
+ /* Align the stack and pass the exit code (from %eax). */
+ andl $0xfffffff0, %esp
+ subl $12, %esp
+ pushl %eax
+
+ call HIDDEN_JUMPTARGET(exit)
/* The 'exit' call should never return. In case it does cause
the process to terminate. */
hlt