Skip to contentSkip to conversation

x86, i387: fix ptrace leakage using init_fpu()

PATCH In review Suresh Siddha 3 participants 3 messages Mar 3, 2008 – Mar 4, 2008 x86

lore
Share & tools
lore

Suresh Siddha

author
#0 lore raw

PATCH 1/1 x86, i387: fix ptrace leakage using init_fpu()

This needs to go into 2.6.25. Thanks.
---

This bug is introduced by the recent i387 merge.

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 <[email protected]>

---

arch/x86/kernel/i387.c +4 -4
index 763dfc4..60fe801 100644
@@ -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)
#2 lore raw
In reply to Suresh Siddha
Quoted 8 lines · Suresh Siddha

This bug is introduced by the recent i387 merge.

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.

thanks Suresh, good catch! Applied to x86.git.

Ingo