Re: [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are not RWX

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From	Heiko Carstens <heiko.carstens@de.ibm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are not RWX
Date	Fri, 26 May 2017 11:40:02 +0200
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On Fri, May 26, 2017 at 09:03:13AM +0200, Thomas Gleixner wrote:
> > It seems like it really should. That would put it in a single place
> > and avoid this mistake again in the future. Does module_memfree() have
> > access to the allocation size, or does that need to get plumbed?
> 
> No, it doesn't. But the number of instances is pretty limited.
> 
> Btw, looking at BPF. It allocates memory via module_alloc() which means
> it's RWX. There is nothing in that BPF code which changes the permissions
> afterwards ....

For BPF you're probably referring to bpf_jit_binary_alloc()? Permissions
are changed with bpf_jit_binary_lock_ro() within each architecure backend.

Well, except for powerpc (cc'ed Michael).

Thread

Re: [PATCH] x86/ftrace: Make sure that ftrace trampolines are not  RWX Thomas Gleixner <tglx@linutronix.de> - 2017-05-25 08:30 +0200
  [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are not  RWX Thomas Gleixner <tglx@linutronix.de> - 2017-05-25 11:00 +0200
    Re: [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are  not RWX Steven Rostedt <rostedt@goodmis.org> - 2017-05-25 17:20 +0200
    Re: [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are not  RWX "Luis R. Rodriguez" <mcgrof@kernel.org> - 2017-05-25 19:50 +0200
      Re: [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are not RWX Kees Cook <keescook@chromium.org> - 2017-05-25 22:00 +0200
        Re: [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are  not RWX Thomas Gleixner <tglx@linutronix.de> - 2017-05-26 09:10 +0200
          Re: [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are not  RWX Heiko Carstens <heiko.carstens@de.ibm.com> - 2017-05-26 11:40 +0200
            Re: [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are  not RWX Thomas Gleixner <tglx@linutronix.de> - 2017-05-26 12:00 +0200
            Re: [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are not RWX Michael Ellerman <mpe@ellerman.id.au> - 2017-05-26 13:50 +0200
        Re: [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are  not RWX Masami Hiramatsu <mhiramat@kernel.org> - 2017-05-26 11:50 +0200
    Re: [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are  not RWX Steven Rostedt <rostedt@goodmis.org> - 2017-05-26 15:40 +0200
      Re: [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are  not RWX Steven Rostedt <rostedt@goodmis.org> - 2017-05-26 16:00 +0200
      Re: [PATCH V2] x86/ftrace: Make sure that ftrace trampolines are  not RWX Thomas Gleixner <tglx@linutronix.de> - 2017-05-26 16:00 +0200

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