This is a note to let you know that I've just added the patch titled
x86/sev-es: Introduce ip_within_syscall_gap() helper
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-sev-es-introduce-ip_within_syscall_gap-helper.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 78a81d88f60ba773cbe890205e1ee67f00502948 Mon Sep 17 00:00:00 2001
From: Joerg Roedel <jroedel@xxxxxxx>
Date: Wed, 3 Mar 2021 15:17:12 +0100
Subject: x86/sev-es: Introduce ip_within_syscall_gap() helper
From: Joerg Roedel <jroedel@xxxxxxx>
commit 78a81d88f60ba773cbe890205e1ee67f00502948 upstream.
Introduce a helper to check whether an exception came from the syscall
gap and use it in the SEV-ES code. Extend the check to also cover the
compatibility SYSCALL entry path.
Fixes: 315562c9af3d5 ("x86/sev-es: Adjust #VC IST Stack on entering NMI handler")
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # 5.10+
Link: https://lkml.kernel.org/r/20210303141716.29223-2-joro@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/entry/entry_64_compat.S | 2 ++
arch/x86/include/asm/proto.h | 1 +
arch/x86/include/asm/ptrace.h | 15 +++++++++++++++
arch/x86/kernel/traps.c | 3 +--
4 files changed, 19 insertions(+), 2 deletions(-)
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -210,6 +210,8 @@ SYM_CODE_START(entry_SYSCALL_compat)
/* Switch to the kernel stack */
movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
+SYM_INNER_LABEL(entry_SYSCALL_compat_safe_stack, SYM_L_GLOBAL)
+
/* Construct struct pt_regs on stack */
pushq $__USER32_DS /* pt_regs->ss */
pushq %r8 /* pt_regs->sp */
--- a/arch/x86/include/asm/proto.h
+++ b/arch/x86/include/asm/proto.h
@@ -25,6 +25,7 @@ void __end_SYSENTER_singlestep_region(vo
void entry_SYSENTER_compat(void);
void __end_entry_SYSENTER_compat(void);
void entry_SYSCALL_compat(void);
+void entry_SYSCALL_compat_safe_stack(void);
void entry_INT80_compat(void);
#ifdef CONFIG_XEN_PV
void xen_entry_INT80_compat(void);
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -94,6 +94,8 @@ struct pt_regs {
#include <asm/paravirt_types.h>
#endif
+#include <asm/proto.h>
+
struct cpuinfo_x86;
struct task_struct;
@@ -175,6 +177,19 @@ static inline bool any_64bit_mode(struct
#ifdef CONFIG_X86_64
#define current_user_stack_pointer() current_pt_regs()->sp
#define compat_user_stack_pointer() current_pt_regs()->sp
+
+static inline bool ip_within_syscall_gap(struct pt_regs *regs)
+{
+ bool ret = (regs->ip >= (unsigned long)entry_SYSCALL_64 &&
+ regs->ip < (unsigned long)entry_SYSCALL_64_safe_stack);
+
+#ifdef CONFIG_IA32_EMULATION
+ ret = ret || (regs->ip >= (unsigned long)entry_SYSCALL_compat &&
+ regs->ip < (unsigned long)entry_SYSCALL_compat_safe_stack);
+#endif
+
+ return ret;
+}
#endif
static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -686,8 +686,7 @@ asmlinkage __visible noinstr struct pt_r
* In the SYSCALL entry path the RSP value comes from user-space - don't
* trust it and switch to the current kernel stack
*/
- if (regs->ip >= (unsigned long)entry_SYSCALL_64 &&
- regs->ip < (unsigned long)entry_SYSCALL_64_safe_stack) {
+ if (ip_within_syscall_gap(regs)) {
sp = this_cpu_read(cpu_current_top_of_stack);
goto sync;
}
Patches currently in stable-queue which might be from jroedel@xxxxxxx are
queue-5.10/iommu-vt-d-clear-prq-overflow-only-when-prq-is-empty.patch
queue-5.10/x86-sev-es-check-regs-sp-is-trusted-before-adjusting-vc-ist-stack.patch
queue-5.10/iommu-amd-fix-performance-counter-initialization.patch
queue-5.10/x86-sev-es-introduce-ip_within_syscall_gap-helper.patch
queue-5.10/x86-sev-es-use-__copy_from_user_inatomic.patch
queue-5.10/x86-sev-es-correctly-track-irq-states-in-runtime-vc-handler.patch
