[PATCH 5.4 049/203] syscalls/x86: Use the correct function type for sys_ni_syscall

Greg Kroah-Hartman
2020-01-16T23:21:46Z

From: Sami Tolvanen <samitolvanen@google.com>

commit f48f01a92cca09e86d46c91d8edf9d5a71c61727 upstream.

Use the correct function type for sys_ni_syscall() in system
call tables to fix indirect call mismatches with Control-Flow
Integrity (CFI) checking.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Andy 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/20191008224049.115427-5-samitolvanen@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/entry/syscall_32.c | 8 +++-----
arch/x86/entry/syscall_64.c | 14 ++++++++++----
arch/x86/entry/syscalls/syscall_32.tbl | 4 ++--
3 files changed, 15 insertions(+), 11 deletions(-)

--- a/arch/x86/entry/syscall_32.c
+++ b/arch/x86/entry/syscall_32.c
@@ -10,13 +10,11 @@
#ifdef CONFIG_IA32_EMULATION
/* On X86_64, we use struct pt_regs * to pass parameters to syscalls */
#define __SYSCALL_I386(nr, sym, qual) extern asmlinkage long sym(const struct pt_regs *);
-
-/* this is a lie, but it does not hurt as sys_ni_syscall just returns -EINVAL */
-extern asmlinkage long sys_ni_syscall(const struct pt_regs *);
-
+#define __sys_ni_syscall __ia32_sys_ni_syscall
#else /* CONFIG_IA32_EMULATION */
#define __SYSCALL_I386(nr, sym, qual) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long);
extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long);
+#define __sys_ni_syscall sys_ni_syscall
#endif /* CONFIG_IA32_EMULATION */

#include <asm/syscalls_32.h>
@@ -29,6 +27,6 @@ __visible const sys_call_ptr_t ia32_sys_
* Smells like a compiler bug -- it doesn't work
* when the & below is removed.
*/
- [0 ... __NR_syscall_compat_max] = &sys_ni_syscall,
+ [0 ... __NR_syscall_compat_max] = &__sys_ni_syscall,
#include <asm/syscalls_32.h>
};
--- a/arch/x86/entry/syscall_64.c
+++ b/arch/x86/entry/syscall_64.c
@@ -4,11 +4,17 @@
#include <linux/linkage.h>
#include <linux/sys.h>
#include <linux/cache.h>
+#include <linux/syscalls.h>
#include <asm/asm-offsets.h>
#include <asm/syscall.h>

-/* this is a lie, but it does not hurt as sys_ni_syscall just returns -EINVAL */
-extern asmlinkage long sys_ni_syscall(const struct pt_regs *);
+extern asmlinkage long sys_ni_syscall(void);
+
+SYSCALL_DEFINE0(ni_syscall)
+{
+ return sys_ni_syscall();
+}
+
#define __SYSCALL_64(nr, sym, qual) extern asmlinkage long sym(const struct pt_regs *);
#define __SYSCALL_X32(nr, sym, qual) __SYSCALL_64(nr, sym, qual)
#include <asm/syscalls_64.h>
@@ -23,7 +29,7 @@ asmlinkage const sys_call_ptr_t sys_call
* Smells like a compiler bug -- it doesn't work
* when the & below is removed.
*/
- [0 ... __NR_syscall_max] = &sys_ni_syscall,
+ [0 ... __NR_syscall_max] = &__x64_sys_ni_syscall,
#include <asm/syscalls_64.h>
};

@@ -40,7 +46,7 @@ asmlinkage const sys_call_ptr_t x32_sys_
* Smells like a compiler bug -- it doesn't work
* when the & below is removed.
*/
- [0 ... __NR_syscall_x32_max] = &sys_ni_syscall,
+ [0 ... __NR_syscall_x32_max] = &__x64_sys_ni_syscall,
#include <asm/syscalls_64.h>
};

--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -124,7 +124,7 @@
110 i386 iopl sys_iopl __ia32_sys_iopl
111 i386 vhangup sys_vhangup __ia32_sys_vhangup
112 i386 idle
-113 i386 vm86old sys_vm86old sys_ni_syscall
+113 i386 vm86old sys_vm86old __ia32_sys_ni_syscall
114 i386 wait4 sys_wait4 __ia32_compat_sys_wait4
115 i386 swapoff sys_swapoff __ia32_sys_swapoff
116 i386 sysinfo sys_sysinfo __ia32_compat_sys_sysinfo
@@ -177,7 +177,7 @@
163 i386 mremap sys_mremap __ia32_sys_mremap
164 i386 setresuid sys_setresuid16 __ia32_sys_setresuid16
165 i386 getresuid sys_getresuid16 __ia32_sys_getresuid16
-166 i386 vm86 sys_vm86 sys_ni_syscall
+166 i386 vm86 sys_vm86 __ia32_sys_ni_syscall
167 i386 query_module
168 i386 poll sys_poll __ia32_sys_poll
169 i386 nfsservctl