Messages in this thread Patch in this message | | | From | Lai Jiangshan <> | Subject | [PATCH 3/3] x86/sev: The code for returning to user space is also in syscall gap | Date | Mon, 13 Dec 2021 12:22:15 +0800 |
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From: Lai Jiangshan <laijs@linux.alibaba.com>
When returning to user space, the %rsp is user controlled value.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com> --- arch/x86/entry/entry_64.S | 2 ++ arch/x86/entry/entry_64_compat.S | 2 ++ arch/x86/include/asm/proto.h | 4 ++++ arch/x86/include/asm/ptrace.h | 4 ++++ 4 files changed, 12 insertions(+)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index e23319ad3f42..44dadea935f7 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -213,8 +213,10 @@ syscall_return_via_sysret: popq %rdi popq %rsp +SYM_INNER_LABEL(entry_SYSRETQ_unsafe_stack, SYM_L_GLOBAL) swapgs sysretq +SYM_INNER_LABEL(entry_SYSRETQ_end, SYM_L_GLOBAL) SYM_CODE_END(entry_SYSCALL_64) /* diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S index 0051cf5c792d..98afdf92f360 100644 --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -293,6 +293,7 @@ sysret32_from_system_call: * code. We zero R8-R10 to avoid info leaks. */ movq RSP-ORIG_RAX(%rsp), %rsp +SYM_INNER_LABEL(entry_SYSRETL_compat_unsafe_stack, SYM_L_GLOBAL) /* * The original userspace %rsp (RSP-ORIG_RAX(%rsp)) is stored @@ -310,6 +311,7 @@ sysret32_from_system_call: xorl %r10d, %r10d swapgs sysretl +SYM_INNER_LABEL(entry_SYSRETL_compat_end, SYM_L_GLOBAL) SYM_CODE_END(entry_SYSCALL_compat) /* diff --git a/arch/x86/include/asm/proto.h b/arch/x86/include/asm/proto.h index feed36d44d04..f042cfc9938f 100644 --- a/arch/x86/include/asm/proto.h +++ b/arch/x86/include/asm/proto.h @@ -13,6 +13,8 @@ void syscall_init(void); #ifdef CONFIG_X86_64 void entry_SYSCALL_64(void); void entry_SYSCALL_64_safe_stack(void); +void entry_SYSRETQ_unsafe_stack(void); +void entry_SYSRETQ_end(void); long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2); #endif @@ -28,6 +30,8 @@ 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_SYSRETL_compat_unsafe_stack(void); +void entry_SYSRETL_compat_end(void); void entry_INT80_compat(void); #ifdef CONFIG_XEN_PV void xen_entry_INT80_compat(void); diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h index 703663175a5a..b3d2ba13cee2 100644 --- a/arch/x86/include/asm/ptrace.h +++ b/arch/x86/include/asm/ptrace.h @@ -186,9 +186,13 @@ static __always_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); + ret = ret || (regs->ip >= (unsigned long)entry_SYSRETQ_unsafe_stack && + regs->ip < (unsigned long)entry_SYSRETQ_end); #ifdef CONFIG_IA32_EMULATION ret = ret || (regs->ip >= (unsigned long)entry_SYSCALL_compat && regs->ip < (unsigned long)entry_SYSCALL_compat_safe_stack); + ret = ret || (regs->ip >= (unsigned long)entry_SYSRETL_compat_unsafe_stack && + regs->ip < (unsigned long)entry_SYSRETL_compat_end); #endif return ret; -- 2.19.1.6.gb485710b
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