From: Andi Kleen <[email protected]> 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 <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: [email protected] Cc: Andy Lutomirski <[email protected]> Signed-off-by: Andi Kleen <[email protected]> Signed-off-by: Dan Williams <[email protected]> --- 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
