Commit 6e484764 authored by Sami Tolvanen's avatar Sami Tolvanen Committed by Ingo Molnar
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syscalls/x86: Fix function types in COND_SYSCALL



Define a weak function in COND_SYSCALL instead of a weak alias to
sys_ni_syscall(), which has an incompatible type. This fixes indirect
call mismatches with Control-Flow Integrity (CFI) checking.

Signed-off-by: default avatarSami Tolvanen <samitolvanen@google.com>
Acked-by: default avatarAndy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H . Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191008224049.115427-6-samitolvanen@google.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent f48f01a9
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+16 −5
Original line number Diff line number Diff line
@@ -6,6 +6,8 @@
#ifndef _ASM_X86_SYSCALL_WRAPPER_H
#define _ASM_X86_SYSCALL_WRAPPER_H

struct pt_regs;

/* Mapping of registers to parameters for syscalls on x86-64 and x32 */
#define SC_X86_64_REGS_TO_ARGS(x, ...)					\
	__MAP(x,__SC_ARGS						\
@@ -65,8 +67,14 @@
	asmlinkage long __x64_sys_##sname(const struct pt_regs *__unused)

#define COND_SYSCALL(name)							\
	cond_syscall(__x64_sys_##name);					\
	cond_syscall(__ia32_sys_##name)
	asmlinkage __weak long __x64_sys_##name(const struct pt_regs *__unused)	\
	{									\
		return sys_ni_syscall();					\
	}									\
	asmlinkage __weak long __ia32_sys_##name(const struct pt_regs *__unused)\
	{									\
		return sys_ni_syscall();					\
	}

#define SYS_NI(name)							\
	SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers);		\
@@ -218,7 +226,11 @@
#endif

#ifndef COND_SYSCALL
#define COND_SYSCALL(name) cond_syscall(__x64_sys_##name)
#define COND_SYSCALL(name) 							\
	asmlinkage __weak long __x64_sys_##name(const struct pt_regs *__unused)	\
	{									\
		return sys_ni_syscall();					\
	}
#endif

#ifndef SYS_NI
@@ -230,7 +242,6 @@
 * For VSYSCALLS, we need to declare these three syscalls with the new
 * pt_regs-based calling convention for in-kernel use.
 */
struct pt_regs;
asmlinkage long __x64_sys_getcpu(const struct pt_regs *regs);
asmlinkage long __x64_sys_gettimeofday(const struct pt_regs *regs);
asmlinkage long __x64_sys_time(const struct pt_regs *regs);