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| author | H. Peter Anvin (Intel) <hpa@zytor.com> | 2021-05-18 22:13:02 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2021-05-20 16:19:49 +0300 |
| commit | b337b4965e3a3e567f11828a9e3fe3fb3faefa47 (patch) | |
| tree | a4c91b73913de17052f31c4335939dcc04a5ee80 /arch/x86/entry | |
| parent | 0595494891723a1dcca5eaa8eeca8ab54ad953b9 (diff) | |
| download | linux-b337b4965e3a3e567f11828a9e3fe3fb3faefa47.tar.xz | |
x86/entry: Treat out of range and gap system calls the same
The current 64-bit system call entry code treats out-of-range system
calls differently than system calls that map to a hole in the system
call table.
This is visible to the user if system calls are intercepted via ptrace or
seccomp and the return value (regs->ax) is modified: in the former case,
the return value is preserved, and in the latter case, sys_ni_syscall() is
called and the return value is forced to -ENOSYS.
The API spec in <asm-generic/syscalls.h> is very clear that only
(int)-1 is the non-system-call sentinel value, so make the system call
behavior consistent by calling sys_ni_syscall() for all invalid system
call numbers except for -1.
Although currently sys_ni_syscall() simply returns -ENOSYS, calling it
explicitly is friendly for tracing and future possible extensions, and
as this is an error path there is no reason to optimize it.
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210518191303.4135296-6-hpa@zytor.com
Diffstat (limited to 'arch/x86/entry')
| -rw-r--r-- | arch/x86/entry/common.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 00da0f5420de..f51bc17262db 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -52,6 +52,8 @@ __visible noinstr void do_syscall_64(struct pt_regs *regs, unsigned long nr) X32_NR_syscalls); regs->ax = x32_sys_call_table[nr](regs); #endif + } else if (unlikely((int)nr != -1)) { + regs->ax = __x64_sys_ni_syscall(regs); } instrumentation_end(); syscall_exit_to_user_mode(regs); @@ -76,6 +78,8 @@ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs, if (likely(nr < IA32_NR_syscalls)) { nr = array_index_nospec(nr, IA32_NR_syscalls); regs->ax = ia32_sys_call_table[nr](regs); + } else if (unlikely((int)nr != -1)) { + regs->ax = __ia32_sys_ni_syscall(regs); } } |