x86, i387: fix ptrace leakage using init_fpu()

This bug got introduced by the recent i387 merge:

  commit 4421011120b2304e5c248ae4165a2704588aedf1
  Author: Roland McGrath <roland@redhat.com>
  Date:   Wed Jan 30 13:31:50 2008 +0100

      x86: x86 i387 user_regset

Current usage of unlazy_fpu() in ptrace specific routines is wrong.
unlazy_fpu() will not init fpu if the task never used math. So the
ptrace calls can expose the parent tasks FPU data in some cases.

Replace it with the init_fpu() which will init the math state, if the
task never used math before.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 763dfc4..60fe801 100644 (file)
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -132,7 +132,7 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
        if (!cpu_has_fxsr)
                return -ENODEV;
 
-       unlazy_fpu(target);
+       init_fpu(target);
 
        return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
                                   &target->thread.i387.fxsave, 0, -1);
@@ -147,7 +147,7 @@ int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
        if (!cpu_has_fxsr)
                return -ENODEV;
 
-       unlazy_fpu(target);
+       init_fpu(target);
        set_stopped_child_used_math(target);
 
        ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
@@ -307,7 +307,7 @@ int fpregs_get(struct task_struct *target, const struct user_regset *regset,
        if (!HAVE_HWFP)
                return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
 
-       unlazy_fpu(target);
+       init_fpu(target);
 
        if (!cpu_has_fxsr)
                return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
@@ -332,7 +332,7 @@ int fpregs_set(struct task_struct *target, const struct user_regset *regset,
        if (!HAVE_HWFP)
                return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
 
-       unlazy_fpu(target);
+       init_fpu(target);
        set_stopped_child_used_math(target);
 
        if (!cpu_has_fxsr)