[tip:x86/asm] x86/entry/vm86: Preserve 'orig_ax'

[tip-bot for Brian Gerst <tipbot@zytor.com>]

Commit-ID:  df1ae9a5dc66d9fd57109240042372b1065d984a
Gitweb:     http://git.kernel.org/tip/df1ae9a5dc66d9fd57109240042372b1065d984a
Author:     Brian Gerst <brgerst@gmail.com>
AuthorDate: Sun, 19 Jul 2015 21:09:05 -0400
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 21 Jul 2015 09:12:23 +0200

x86/entry/vm86: Preserve 'orig_ax'

There is no legitimate reason for usermode to modify the 'orig_ax'
field on entry to vm86 mode, so copy it from the 32-bit regs.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1437354550-25858-3-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/vm86_32.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index 761a2f9..9a2dc80 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -294,6 +294,8 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk
 	info->regs.pt.flags |= info->regs32->flags & ~SAFE_MASK;
 	info->regs.pt.flags |= X86_VM_MASK;
 
+	info->regs.pt.orig_ax = info->regs32->orig_ax;
+
 	switch (info->cpu_type) {
 	case CPU_286:
 		tsk->thread.v86mask = 0;