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Re: [PATCH v7 07/26] x86/insn-eval: Do not BUG on invalid register type

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On Fri, May 05, 2017 at 11:17:05AM -0700, Ricardo Neri wrote:
> We are not in a critical failure path. The invalid register type is caused
> when trying to decode invalid instruction bytes from a user-space program.
> Thus, simply print an error message. To prevent this warning from being
> abused from user space programs, use the rate-limited variant of printk.
> 
> Cc: Borislav Petkov <bp@suse.de>
> Cc: Andy Lutomirski <luto@kernel.org>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: Adam Buchbinder <adam.buchbinder@gmail.com>
> Cc: Colin Ian King <colin.king@canonical.com>
> Cc: Lorenzo Stoakes <lstoakes@gmail.com>
> Cc: Qiaowei Ren <qiaowei.ren@intel.com>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Cc: Masami Hiramatsu <mhiramat@kernel.org>
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Thomas Garnier <thgarnie@google.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Ravi V. Shankar <ravi.v.shankar@intel.com>
> Cc: x86@kernel.org
> Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
> ---
>  arch/x86/lib/insn-eval.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c
> index e746a6f..182e2ae 100644
> --- a/arch/x86/lib/insn-eval.c
> +++ b/arch/x86/lib/insn-eval.c
> @@ -5,6 +5,7 @@
>   */
>  #include <linux/kernel.h>
>  #include <linux/string.h>
> +#include <linux/ratelimit.h>
>  #include <asm/inat.h>
>  #include <asm/insn.h>
>  #include <asm/insn-eval.h>
> @@ -85,9 +86,8 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs,
>  		break;
>  
>  	default:
> -		pr_err("invalid register type");
> -		BUG();
> -		break;
> +		printk_ratelimited(KERN_ERR "insn-eval: x86: invalid register type");

You can use pr_err_ratelimited() and define "insn-eval" with pr_fmt.
Look for examples in the tree.

Btw, "insn-eval" is perhaps not the right name - since we're building
an instruction decoder, maybe it should be called "insn-dec" or so. I'm
looking at those other arch/x86/lib/insn.c, arch/x86/include/asm/inat.h
things and how they're starting to morph into one decoding facility,
AFAICT.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
-- 

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Re: [PATCH v7 07/26] x86/insn-eval: Do not BUG on invalid register  type Borislav Petkov <bp@suse.de> - 2017-05-29 18:40 +0200
  Re: [PATCH v7 07/26] x86/insn-eval: Do not BUG on invalid register  type Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-06-06 08:10 +0200
    Re: [PATCH v7 07/26] x86/insn-eval: Do not BUG on invalid register  type Borislav Petkov <bp@suse.de> - 2017-06-06 14:00 +0200
      Re: [PATCH v7 07/26] x86/insn-eval: Do not BUG on invalid register  type Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-06-07 02:30 +0200
        Re: [PATCH v7 07/26] x86/insn-eval: Do not BUG on invalid register  type Borislav Petkov <bp@suse.de> - 2017-06-07 14:30 +0200

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