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  1. 11 2月, 2009 1 次提交
    • T
      x86: fix x86_32 stack protector bugs · 5c79d2a5
      由 Tejun Heo 提交于 
      Impact: fix x86_32 stack protector

Brian Gerst found out that %gs was being initialized to stack_canary
instead of stack_canary - 20, which basically gave the same canary
value for all threads.  Fixing this also exposed the following bugs.

* cpu_idle() didn't call boot_init_stack_canary()

* stack canary switching in switch_to() was being done too late making
  the initial run of a new thread use the old stack canary value.

Fix all of them and while at it update comment in cpu_idle() about
calling boot_init_stack_canary().
Reported-by: NBrian Gerst <brgerst@gmail.com>
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      5c79d2a5
  3. 10 2月, 2009 8 次提交
    • T
      x86: implement x86_32 stack protector · 60a5317f
      由 Tejun Heo 提交于 
      Impact: stack protector for x86_32

Implement stack protector for x86_32.  GDT entry 28 is used for it.
It's set to point to stack_canary-20 and have the length of 24 bytes.
CONFIG_CC_STACKPROTECTOR turns off CONFIG_X86_32_LAZY_GS and sets %gs
to the stack canary segment on entry.  As %gs is otherwise unused by
the kernel, the canary can be anywhere.  It's defined as a percpu
variable.

x86_32 exception handlers take register frame on stack directly as
struct pt_regs.  With -fstack-protector turned on, gcc copies the
whole structure after the stack canary and (of course) doesn't copy
back on return thus losing all changed.  For now, -fno-stack-protector
is added to all files which contain those functions.  We definitely
need something better.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      60a5317f
    • T
      x86: make lazy %gs optional on x86_32 · ccbeed3a
      由 Tejun Heo 提交于 
      Impact: pt_regs changed, lazy gs handling made optional, add slight
        overhead to SAVE_ALL, simplifies error_code path a bit

On x86_32, %gs hasn't been used by kernel and handled lazily.  pt_regs
doesn't have place for it and gs is saved/loaded only when necessary.
In preparation for stack protector support, this patch makes lazy %gs
handling optional by doing the followings.

* Add CONFIG_X86_32_LAZY_GS and place for gs in pt_regs.

* Save and restore %gs along with other registers in entry_32.S unless
  LAZY_GS.  Note that this unfortunately adds "pushl $0" on SAVE_ALL
  even when LAZY_GS.  However, it adds no overhead to common exit path
  and simplifies entry path with error code.

* Define different user_gs accessors depending on LAZY_GS and add
  lazy_save_gs() and lazy_load_gs() which are noop if !LAZY_GS.  The
  lazy_*_gs() ops are used to save, load and clear %gs lazily.

* Define ELF_CORE_COPY_KERNEL_REGS() which always read %gs directly.

xen and lguest changes need to be verified.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      ccbeed3a
    • T
      x86: add %gs accessors for x86_32 · d9a89a26
      由 Tejun Heo 提交于 
      Impact: cleanup

On x86_32, %gs is handled lazily.  It's not saved and restored on
kernel entry/exit but only when necessary which usually is during task
switch but there are few other places.  Currently, it's done by
calling savesegment() and loadsegment() explicitly.  Define
get_user_gs(), set_user_gs() and task_user_gs() and use them instead.

While at it, clean up register access macros in signal.c.

This cleans up code a bit and will help future changes.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      d9a89a26
    • T
      x86: use asm .macro instead of cpp #define in entry_32.S · f0d96110
      由 Tejun Heo 提交于 
      Impact: cleanup

Use .macro instead of cpp #define where approriate.  This cleans up
code and will ease future changes.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      f0d96110
    • T
      x86: no stack protector for vdso · d627ded5
      由 Tejun Heo 提交于 
      Impact: avoid crash on vsyscall
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      d627ded5
    • T
      stackprotector: update make rules · 5d707e9c
      由 Tejun Heo 提交于 
      Impact: no default -fno-stack-protector if stackp is enabled, cleanup

Stackprotector make rules had the following problems.

* cc support test and warning are scattered across makefile and
  kernel/panic.c.

* -fno-stack-protector was always added regardless of configuration.

Update such that cc support test and warning are contained in makefile
and -fno-stack-protector is added iff stackp is turned off.  While at
it, prepare for 32bit support.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      5d707e9c
    • T
      x86: stackprotector.h misc update · 76397f72
      由 Tejun Heo 提交于 
      Impact: misc udpate

* wrap content with CONFIG_CC_STACK_PROTECTOR so that other arch files
  can include it directly

* add missing includes

This will help future changes.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      76397f72
    • T
      x86: fix math_emu register frame access · d315760f
      由 Tejun Heo 提交于 
      do_device_not_available() is the handler for #NM and it declares that
it takes a unsigned long and calls math_emu(), which takes a long
argument and surprisingly expects the stack frame starting at the zero
argument would match struct math_emu_info, which isn't true regardless
of configuration in the current code.

This patch makes do_device_not_available() take struct pt_regs like
other exception handlers and initialize struct math_emu_info with
pointer to it and pass pointer to the math_emu_info to math_emulate()
like normal C functions do.  This way, unless gcc makes a copy of
struct pt_regs in do_device_not_available(), the register frame is
correctly accessed regardless of kernel configuration or compiler
used.

This doesn't fix all math_emu problems but it at least gets it
somewhat working.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      d315760f
  5. 09 2月, 2009 8 次提交
  7. 07 2月, 2009 1 次提交
    • R
      x86-64: fix int $0x80 -ENOSYS return · c09249f8
      由 Roland McGrath 提交于 
      One of my past fixes to this code introduced a different new bug.
When using 32-bit "int $0x80" entry for a bogus syscall number,
the return value is not correctly set to -ENOSYS.  This only happens
when neither syscall-audit nor syscall tracing is enabled (i.e., never
seen if auditd ever started).  Test program:

	/* gcc -o int80-badsys -m32 -g int80-badsys.c
	   Run on x86-64 kernel.
	   Note to reproduce the bug you need auditd never to have started.  */

	#include <errno.h>
	#include <stdio.h>

	int
	main (void)
	{
	  long res;
	  asm ("int $0x80" : "=a" (res) : "0" (99999));
	  printf ("bad syscall returns %ld\n", res);
	  return res != -ENOSYS;
	}

The fix makes the int $0x80 path match the sysenter and syscall paths.
Reported-by: NDmitry V. Levin <ldv@altlinux.org>
Signed-off-by: NRoland McGrath <roland@redhat.com>
      c09249f8
  9. 06 2月, 2009 3 次提交
  11. 05 2月, 2009 11 次提交
  13. 04 2月, 2009 8 次提交