linux-kernel - Re: [PATCH] bug: Fix "cut here" for WARN_ON for __WARN

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Message-ID: <201906240856.0A82D562C@keescook>
Date:   Mon, 24 Jun 2019 08:58:02 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Drew Davenport <ddavenport@...omium.org>, akpm@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] bug: Fix "cut here" for WARN_ON for __WARN_TAINT
 architectures

On Mon, Jun 24, 2019 at 09:48:31AM -0600, Drew Davenport wrote:
> For architectures using __WARN_TAINT, the WARN_ON macro did not
> print out the "cut here" string. The other WARN_XXX macros would
> print "cut here" inside __warn_printk, which is not called for
> WARN_ON since it doesn't have a message to print.
> 
> Fixes: a7bed27af194 ("bug: fix "cut here" location for __WARN_TAINT architectures")
> Cc: stable@...r.kernel.org
> Signed-off-by: Drew Davenport <ddavenport@...omium.org>

Whoops, yes; thanks for catching this!

Acked-and-Tested-by: Kees Cook <keescook@...omium.org>

-Kees

> ---
>  include/asm-generic/bug.h | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
> index c21ff2712803..79feb1a3081b 100644
> --- a/include/asm-generic/bug.h
> +++ b/include/asm-generic/bug.h
> @@ -94,8 +94,10 @@ extern void warn_slowpath_null(const char *file, const int line);
>  	warn_slowpath_fmt_taint(__FILE__, __LINE__, taint, arg)
>  #else
>  extern __printf(1, 2) void __warn_printk(const char *fmt, ...);
> -#define __WARN()		__WARN_TAINT(TAINT_WARN)
> -#define __WARN_printf(arg...)	do { __warn_printk(arg); __WARN(); } while (0)
> +#define __WARN() do { \
> +	printk(KERN_WARNING CUT_HERE); __WARN_TAINT(TAINT_WARN); \
> +} while (0)
> +#define __WARN_printf(arg...)	__WARN_printf_taint(TAINT_WARN, arg)
>  #define __WARN_printf_taint(taint, arg...)				\
>  	do { __warn_printk(arg); __WARN_TAINT(taint); } while (0)
>  #endif
> -- 
> 2.20.1
> 

-- 
Kees Cook