commit 8a5df95ffa83f525a4f638ead743f4fa2b7fe45a Author: Florian Weimer 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 + . */ + +#include +#include +#include +#include +#include +#include +#include +#include + +/* 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 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