Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1426889
| From | Oleg Nesterov <oleg@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | the usage of __SYSCALL_MASK in entry_SYSCALL_64/do_syscall_64 is not consistent |
| Date | 2016-06-20 20:10 +0200 |
| Message-ID | <rMbO2-3aM-15@gated-at.bofh.it> (permalink) |
| References | <rLlFL-2MV-1@gated-at.bofh.it> <rLTo6-8jU-7@gated-at.bofh.it> <rM0IW-4CS-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 06/19, Andy Lutomirski wrote:
>
> Something's clearly buggy there,
The usage of __X32_SYSCALL_BIT doesn't look right too. Nothing serious
but still.
Damn, initially I thought I have found the serious bug in entry_64.S
and it took me some time to understand why my exploit doesn't work ;)
So I learned that
andl $__SYSCALL_MASK, %eax
in entry_SYSCALL_64_fastpath() zero-extends %rax and thus
cmpl $__NR_syscall_max, %eax
...
call *sys_call_table(, %rax, 8)
is correct (rax <= __NR_syscall_max).
OK, so entry_64.S simply "ignores" the upper bits if CONFIG_X86_X32_ABI.
Fine, but this doesn't match the
if (likely((nr & __SYSCALL_MASK) < NR_syscalls))
check in do_syscall_64(). So this test-case
#include <stdio.h>
int main(void)
{
// __NR_exit == 0x3c
asm volatile ("movq $0xFFFFFFFF0000003c, %rax; syscall");
printf("I didn't exit because I am traced\n");
return 0;
}
silently exits if not traced, otherwise it calls printf().
Should we do something or we do not care?
Oleg.
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Andy Lutomirski <luto@kernel.org> - 2016-06-18 12:30 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Pedro Alves <pedro@palves.net> - 2016-06-18 16:00 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Pedro Alves <palves@redhat.com> - 2016-06-18 16:50 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Andy Lutomirski <luto@amacapital.net> - 2016-06-18 19:10 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Andy Lutomirski <luto@amacapital.net> - 2016-06-20 00:20 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Pedro Alves <pedro@palves.net> - 2016-06-20 12:30 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Oleg Nesterov <oleg@redhat.com> - 2016-06-20 18:40 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Andy Lutomirski <luto@amacapital.net> - 2016-06-20 18:50 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Oleg Nesterov <oleg@redhat.com> - 2016-06-20 19:20 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Andy Lutomirski <luto@amacapital.net> - 2016-06-20 19:30 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Pedro Alves <pedro@palves.net> - 2016-06-20 12:10 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Jan Kratochvil <jan.kratochvil@redhat.com> - 2016-06-20 13:20 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Kees Cook <keescook@chromium.org> - 2016-06-18 19:50 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Andy Lutomirski <luto@amacapital.net> - 2016-06-20 00:30 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Oleg Nesterov <oleg@redhat.com> - 2016-06-20 00:30 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Andy Lutomirski <luto@amacapital.net> - 2016-06-20 08:20 +0200
Re: [PATCH] x86/ptrace: Remove questionable TS_COMPAT usage in ptrace Oleg Nesterov <oleg@redhat.com> - 2016-06-20 18:40 +0200
the usage of __SYSCALL_MASK in entry_SYSCALL_64/do_syscall_64 is not consistent Oleg Nesterov <oleg@redhat.com> - 2016-06-20 20:10 +0200
Re: the usage of __SYSCALL_MASK in entry_SYSCALL_64/do_syscall_64 is not consistent Kees Cook <keescook@chromium.org> - 2016-06-21 21:10 +0200
csiph-web