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Subject[tip:x86/pti] x86/vm86/32: Fix POPF emulation
Commit-ID:  b5069782453459f6ec1fdeb495d9901a4545fcb5
Gitweb: https://git.kernel.org/tip/b5069782453459f6ec1fdeb495d9901a4545fcb5
Author: Andy Lutomirski <luto@kernel.org>
AuthorDate: Tue, 13 Mar 2018 22:03:12 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 14 Mar 2018 09:21:01 +0100

x86/vm86/32: Fix POPF emulation

POPF would trap if VIP was set regardless of whether IF was set. Fix it.

Suggested-by: Stas Sergeev <stsp@list.ru>
Reported-by: Bart Oldeman <bartoldeman@gmail.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Fixes: 5ed92a8ab71f ("x86/vm86: Use the normal pt_regs area for vm86")
Link: http://lkml.kernel.org/r/ce95f40556e7b2178b6bc06ee9557827ff94bd28.1521003603.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/vm86_32.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index 5edb27f1a2c4..9d0b5af7db91 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -727,7 +727,8 @@ void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code)
return;

check_vip:
- if (VEFLAGS & X86_EFLAGS_VIP) {
+ if ((VEFLAGS & (X86_EFLAGS_VIP | X86_EFLAGS_VIF)) ==
+ (X86_EFLAGS_VIP | X86_EFLAGS_VIF)) {
save_v86_state(regs, VM86_STI);
return;
}
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