[PATCH v2 3/3] x86/entry: Clear registers for compat syscalls

[Dan Williams]

From: Andi Kleen 

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 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: x...@kernel.org
Cc: Andy Lutomirski 
Signed-off-by: Andi Kleen 
Signed-off-by: Dan Williams 
---
 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

[PATCH v2 3/3] x86/entry: Clear registers for compat syscalls

[Dan Williams]

From: Andi Kleen 

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 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: x...@kernel.org
Cc: Andy Lutomirski 
Signed-off-by: Andi Kleen 
Signed-off-by: Dan Williams 
---
 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