Re: [v2 3/7] x86/mpx, x86/insn: Relocate insn util functions to a new insn-utils
On Tue, 2017-01-03 at 08:44 -0800, Dave Hansen wrote: > On 12/23/2016 05:37 PM, Ricardo Neri wrote: > > Other kernel submodules can benefit from using the utility functions > > defined in mpx.c to obtain the addresses and values of operands contained > > in the general purpose registers. An instance of this is the emulation code > > used for instructions protected by the Intel User-Mode Instruction > > Prevention feature. > > I haven't looked at this in detail, but as long as this is pretty much a > straight code move, I don't see any issues with it from an MPX > perspective. I'm glad to see it getting reused. Yes, this is only a relocation of code. > > Feel free to add my Acked-by on it if you like. Great! Thanks! Ricardo -- To unsubscribe from this list: send the line "unsubscribe linux-msdos" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [v2 2/7] x86/mpx: Fail when implicit zero-displacement is used along with R/EBP
On 12/27/2016 02:33 PM, Ricardo Neri wrote:
>>> diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
>>> index 6a75a75..71681d0 100644
>>> --- a/arch/x86/mm/mpx.c
>>> +++ b/arch/x86/mm/mpx.c
>>> @@ -120,6 +120,13 @@ static int get_reg_offset(struct insn *insn, struct
>>> pt_regs *regs,
>>>
>>> case REG_TYPE_BASE:
>>> regno = X86_SIB_BASE(insn->sib.value);
>>> + if (regno == 5 && X86_MODRM_RM(insn->modrm.value) == 0) {
>>> + WARN_ONCE(1, "An explicit displacement is required
>>> when %sBP used as SIB base.",
>>> + (IS_ENABLED(CONFIG_X86_64) &&
>>> insn->x86_64) ?
>>> + "R13 or R" : "E");
>>> + return -EINVAL;
>>> + }
>>> +
>> Now that I've read the cover letter, I see what's going on. This
>> should not warn -- user code can easily trigger this deliberately.
> OK, I'll remove it. Are you concerned about the warning printing the
> calltrace, even only once?
Yes. We don't let userspace spam the kernel, even once. If we have a
couple thousand "only once" places, then userspace can overwhelm the
kernel log.
Also, this needs a much better description of what's going on in the
code. Could you add a comment explaining what's going on, and why
regno==5, etc...?
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Re: [v2 3/7] x86/mpx, x86/insn: Relocate insn util functions to a new insn-utils
On 12/23/2016 05:37 PM, Ricardo Neri wrote: > Other kernel submodules can benefit from using the utility functions > defined in mpx.c to obtain the addresses and values of operands contained > in the general purpose registers. An instance of this is the emulation code > used for instructions protected by the Intel User-Mode Instruction > Prevention feature. I haven't looked at this in detail, but as long as this is pretty much a straight code move, I don't see any issues with it from an MPX perspective. I'm glad to see it getting reused. Feel free to add my Acked-by on it if you like. -- To unsubscribe from this list: send the line "unsubscribe linux-msdos" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
