diff options
| author | Denys Vlasenko <dvlasenk@redhat.com> | 2015-04-04 20:55:19 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-04-06 09:24:08 +0200 |
| commit | fc3e958a2b552fe6210e6de3bebb4348156a0b5f (patch) | |
| tree | faa91925b07208febff9ad6dcda4dac17f9c9c59 /arch/x86/kernel/entry_64.S | |
| parent | 6a3713f001b3b53587e411ab0d3036ae9b0fb93b (diff) | |
x86/asm/entry: Clear EXTRA_REGS for all executable formats
On failure, sys_execve() does not clobber EXTRA_REGS, so we can
just return to userpsace without saving/restoring them.
On success, ELF_PLAT_INIT() in sys_execve() clears all these
registers.
On other executable formats:
- binfmt_flat.c has similar FLAT_PLAT_INIT, but x86 (and everyone
else except sh) doesn't define it.
- binfmt_elf_fdpic.c has ELF_FDPIC_PLAT_INIT, but x86 (and most
others) doesn't define it.
- There are no such hooks in binfmt_aout.c et al. We inherit
EXTRA_REGS from the prior executable.
This inconsistency was not intended.
This change removes SAVE/RESTORE_EXTRA_REGS in stub_execve,
removes register clearing in ELF_PLAT_INIT(),
and instead simply clears them on success in stub_execve.
Run-tested.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1428173719-7637-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/entry_64.S')
| -rw-r--r-- | arch/x86/kernel/entry_64.S | 50 |
1 files changed, 22 insertions, 28 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 386375d43d14..f4270ff73f2a 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -419,25 +419,27 @@ END(stub_\func) ENTRY(stub_execve) CFI_STARTPROC - addq $8, %rsp - DEFAULT_FRAME 0 - SAVE_EXTRA_REGS - call sys_execve - movq %rax,RAX(%rsp) - RESTORE_EXTRA_REGS - jmp int_ret_from_sys_call + DEFAULT_FRAME 0, 8 + call sys_execve +return_from_execve: + testl %eax, %eax + jz 1f + /* exec failed, can use fast SYSRET code path in this case */ + ret +1: + /* must use IRET code path (pt_regs->cs may have changed) */ + addq $8, %rsp + ZERO_EXTRA_REGS + movq %rax,RAX(%rsp) + jmp int_ret_from_sys_call CFI_ENDPROC END(stub_execve) ENTRY(stub_execveat) CFI_STARTPROC - addq $8, %rsp - DEFAULT_FRAME 0 - SAVE_EXTRA_REGS - call sys_execveat - movq %rax,RAX(%rsp) - RESTORE_EXTRA_REGS - jmp int_ret_from_sys_call + DEFAULT_FRAME 0, 8 + call sys_execveat + jmp return_from_execve CFI_ENDPROC END(stub_execveat) @@ -472,25 +474,17 @@ END(stub_x32_rt_sigreturn) ENTRY(stub_x32_execve) CFI_STARTPROC - addq $8, %rsp - DEFAULT_FRAME 0 - SAVE_EXTRA_REGS - call compat_sys_execve - movq %rax,RAX(%rsp) - RESTORE_EXTRA_REGS - jmp int_ret_from_sys_call + DEFAULT_FRAME 0, 8 + call compat_sys_execve + jmp return_from_execve CFI_ENDPROC END(stub_x32_execve) ENTRY(stub_x32_execveat) CFI_STARTPROC - addq $8, %rsp - DEFAULT_FRAME 0 - SAVE_EXTRA_REGS - call compat_sys_execveat - movq %rax,RAX(%rsp) - RESTORE_EXTRA_REGS - jmp int_ret_from_sys_call + DEFAULT_FRAME 0, 8 + call compat_sys_execveat + jmp return_from_execve CFI_ENDPROC END(stub_x32_execveat) |