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>

diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index 761a2f9..9a2dc80 100644 (file)
--- 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;