When returning to user space, %rsp is user-controlled value.
If it is a SNP-guest and the hypervisor decides to mess with the
code-page for this path while a CPU is executing it, a potential #VC
could hit in the syscall return path and mislead the #VC handler.
So make ip_within_syscall_gap() return true in this case.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20220412124909.10467-1-jiangshanlai@gmail.com
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)
/*
* 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
xorl %r10d, %r10d
swapgs
sysretl
+SYM_INNER_LABEL(entry_SYSRETL_compat_end, SYM_L_GLOBAL)
SYM_CODE_END(entry_SYSCALL_compat)
/*
#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
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);
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;