From: Andi Kleen <a...@linux.intel.com>
At entry userspace may have populated registers with values that could
be useful in a speculative execution attack. Clear them to minimize the
kernel's attack surface.
[djbw: rename the macro, only clear the extra registers]
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: x...@kernel.org
Cc: Andy Lutomirski <l...@kernel.org>
Signed-off-by: Andi Kleen <a...@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
---
arch/x86/entry/entry_64_compat.S | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 98d5358e4041..f55b018a580b 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -95,6 +95,7 @@ ENTRY(entry_SYSENTER_compat)
pushq $0 /* pt_regs->r14 = 0 */
pushq $0 /* pt_regs->r15 = 0 */
cld
+ CLEAR_EXTRA_REGS_NOSPEC
/*
* SYSENTER doesn't filter flags, so we need to clear NT and AC
@@ -223,6 +224,7 @@ GLOBAL(entry_SYSCALL_compat_after_hwframe)
pushq $0 /* pt_regs->r13 = 0 */
pushq $0 /* pt_regs->r14 = 0 */
pushq $0 /* pt_regs->r15 = 0 */
+ CLEAR_EXTRA_REGS_NOSPEC
/*
* User mode is traced as though IRQs are on, and SYSENTER
@@ -348,6 +350,7 @@ ENTRY(entry_INT80_compat)
pushq %r14 /* pt_regs->r14 */
pushq %r15 /* pt_regs->r15 */
cld
+ CLEAR_EXTRA_REGS_NOSPEC
/*
* User mode is traced as though IRQs are on, and the interrupt
