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Subject[RFC][PATCH 09/22] x86: switch save_v86_state() to unsafe_put_user()
Date
From: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
arch/x86/kernel/vm86_32.c | 61 +++++++++++++++++++++++------------------------
1 file changed, 30 insertions(+), 31 deletions(-)

diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index 49b37eb01e99..47a8676c7395 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -98,7 +98,6 @@ void save_v86_state(struct kernel_vm86_regs *regs, int retval)
struct task_struct *tsk = current;
struct vm86plus_struct __user *user;
struct vm86 *vm86 = current->thread.vm86;
- long err = 0;

/*
* This gets called from entry.S with interrupts disabled, but
@@ -114,37 +113,30 @@ void save_v86_state(struct kernel_vm86_regs *regs, int retval)
set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | vm86->veflags_mask);
user = vm86->user_vm86;

- if (!access_ok(user, vm86->vm86plus.is_vm86pus ?
+ if (!user_access_begin(user, vm86->vm86plus.is_vm86pus ?
sizeof(struct vm86plus_struct) :
- sizeof(struct vm86_struct))) {
- pr_alert("could not access userspace vm86 info\n");
- do_exit(SIGSEGV);
- }
-
- put_user_try {
- put_user_ex(regs->pt.bx, &user->regs.ebx);
- put_user_ex(regs->pt.cx, &user->regs.ecx);
- put_user_ex(regs->pt.dx, &user->regs.edx);
- put_user_ex(regs->pt.si, &user->regs.esi);
- put_user_ex(regs->pt.di, &user->regs.edi);
- put_user_ex(regs->pt.bp, &user->regs.ebp);
- put_user_ex(regs->pt.ax, &user->regs.eax);
- put_user_ex(regs->pt.ip, &user->regs.eip);
- put_user_ex(regs->pt.cs, &user->regs.cs);
- put_user_ex(regs->pt.flags, &user->regs.eflags);
- put_user_ex(regs->pt.sp, &user->regs.esp);
- put_user_ex(regs->pt.ss, &user->regs.ss);
- put_user_ex(regs->es, &user->regs.es);
- put_user_ex(regs->ds, &user->regs.ds);
- put_user_ex(regs->fs, &user->regs.fs);
- put_user_ex(regs->gs, &user->regs.gs);
-
- put_user_ex(vm86->screen_bitmap, &user->screen_bitmap);
- } put_user_catch(err);
- if (err) {
- pr_alert("could not access userspace vm86 info\n");
- do_exit(SIGSEGV);
- }
+ sizeof(struct vm86_struct)))
+ goto Efault;
+
+ unsafe_put_user(regs->pt.bx, &user->regs.ebx, Efault_end);
+ unsafe_put_user(regs->pt.cx, &user->regs.ecx, Efault_end);
+ unsafe_put_user(regs->pt.dx, &user->regs.edx, Efault_end);
+ unsafe_put_user(regs->pt.si, &user->regs.esi, Efault_end);
+ unsafe_put_user(regs->pt.di, &user->regs.edi, Efault_end);
+ unsafe_put_user(regs->pt.bp, &user->regs.ebp, Efault_end);
+ unsafe_put_user(regs->pt.ax, &user->regs.eax, Efault_end);
+ unsafe_put_user(regs->pt.ip, &user->regs.eip, Efault_end);
+ unsafe_put_user(regs->pt.cs, &user->regs.cs, Efault_end);
+ unsafe_put_user(regs->pt.flags, &user->regs.eflags, Efault_end);
+ unsafe_put_user(regs->pt.sp, &user->regs.esp, Efault_end);
+ unsafe_put_user(regs->pt.ss, &user->regs.ss, Efault_end);
+ unsafe_put_user(regs->es, &user->regs.es, Efault_end);
+ unsafe_put_user(regs->ds, &user->regs.ds, Efault_end);
+ unsafe_put_user(regs->fs, &user->regs.fs, Efault_end);
+ unsafe_put_user(regs->gs, &user->regs.gs, Efault_end);
+ unsafe_put_user(vm86->screen_bitmap, &user->screen_bitmap, Efault_end);
+
+ user_access_end();

preempt_disable();
tsk->thread.sp0 = vm86->saved_sp0;
@@ -159,6 +151,13 @@ void save_v86_state(struct kernel_vm86_regs *regs, int retval)
lazy_load_gs(vm86->regs32.gs);

regs->pt.ax = retval;
+ return;
+
+Efault_end:
+ user_access_end();
+Efault:
+ pr_alert("could not access userspace vm86 info\n");
+ do_exit(SIGSEGV);
}

static void mark_screen_rdonly(struct mm_struct *mm)
--
2.11.0
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