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SubjectRe: [RFC PATCH tip/master V3 0/8] kprobes/x86: Make kprobes instruction buffers read-only
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On Wed, 29 Mar 2017 13:55:44 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:

> Hi,
>
> This is the 3rd version of the series. I just updated 4/8 according
> to Ingo's comment.
>
> This series tries to make kprobes instruction buffers read-only
> pages. Since those buffers are used for trampoline code, those
> are a part of "text area" and it should be marked as ro for
> avoiding unexpected modification. And this actually fix a warning
> rodata sanity check reported by lkp-robot.
>
> https://lkml.org/lkml/2017/2/27/161
>
> This change requires changing the kprobe-booster at first
> because it can modify the instruction buffer to add a jump while
> resuming from single-stepping. Of course after we make the buffer
> readonly, we may not be able to modify it while probing.
>
> So, at first this series checks the current bootable instructions
> and fixes a missed instruction (call far), modifies can_boost to
> use x86 instruction decoder, and inserts "booster" jump while
> preparing instruction buffer instead of resuming from single-stepping.
> At last, it makes the buffers for kprobes and optprobe readonly.
>
> This series also has some cleanup patches related to above
> changes.
>
> Changes from V2:
> - [4/8]: Fix imbalanced curly braces and remove unneeded
> (void *) cast.
>
> ---
>
> Masami Hiramatsu (8):
> kprobes/x86: Fix not to boost call far instruction
> kprobes/x86: Fix the description of __copy_instruction()
> kprobes/x86: Use instruction decoder for booster
> kprobes/x86: Do not modify singlestep buffer while resuming
> kprobes/x86: Make boostable flag boolean
> kprobes/x86: Set kprobes pages readonly
> kprobes/x86: Use probe_kernel_read instead of memcpy
> kprobes/x86: Consolidate insn decoder users for copying code
>
>
> arch/x86/include/asm/kprobes.h | 7 +-
> arch/x86/kernel/kprobes/common.h | 4 +
> arch/x86/kernel/kprobes/core.c | 149 +++++++++++++++++++-------------------
> arch/x86/kernel/kprobes/ftrace.c | 2 -
> arch/x86/kernel/kprobes/opt.c | 13 +++
> 5 files changed, 90 insertions(+), 85 deletions(-)
>
> --
> Masami Hiramatsu (Linaro) <mhiramat@kernel.org>


--
Masami Hiramatsu <mhiramat@kernel.org>

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