[PATCH 05/22] x86/entry/vm86: Preserve 'orig_ax'

[tim.gardner at canonical.com]

From: Brian Gerst <brgerst at gmail.com>

BugLink: http://bugs.launchpad.net/bugs/1499089

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 at gmail.com>
Cc: Andy Lutomirski <luto at amacapital.net>
Cc: Denys Vlasenko <dvlasenk at redhat.com>
Cc: Linus Torvalds <torvalds at linux-foundation.org>
Cc: Peter Zijlstra <peterz at infradead.org>
Cc: Thomas Gleixner <tglx at linutronix.de>
Link: http://lkml.kernel.org/r/1437354550-25858-3-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo at kernel.org>
(cherry picked from commit df1ae9a5dc66d9fd57109240042372b1065d984a)
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
---
 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;
-- 
1.9.1