linux-kernel - Re: [patch] x86, AMD, NB: silence an underflow test

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Message-ID: <20140121100257.GB9004@pd.tnic>
Date:	Tue, 21 Jan 2014 11:02:57 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Dan Carpenter <dan.carpenter@...cle.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Daniel J Blueman <daniel@...ascale-asia.com>,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [patch] x86, AMD, NB: silence an underflow test

On Tue, Jan 21, 2014 at 10:22:09AM +0300, Dan Carpenter wrote:
> This is under CAP_SYS_ADMIN but Smatch complains that mask comes from

"Smatch complains..." - you sound just like a politician - something
inanimate and abstract complains that something's wrong - I'm not to
blame, I'm innocent!

Not "amd_set_subcaches should hand down an unsigned long like it was
originally indended but then bugged into an int..."

:-) :-) :-)

> the user and the test for "mask > 0xf" can underflow.  The fix is
> simple.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>

In any case:

Acked-by: Borislav Petkov <bp@...e.de>

Thanks!

> diff --git a/arch/x86/include/asm/amd_nb.h b/arch/x86/include/asm/amd_nb.h
> index a54ee1d054d9..0c4e3e47d462 100644
> --- a/arch/x86/include/asm/amd_nb.h
> +++ b/arch/x86/include/asm/amd_nb.h
> @@ -19,7 +19,7 @@ extern int amd_cache_northbridges(void);
>  extern void amd_flush_garts(void);
>  extern int amd_numa_init(void);
>  extern int amd_get_subcaches(int);
> -extern int amd_set_subcaches(int, int);
> +extern int amd_set_subcaches(int, unsigned long);
>  
>  struct amd_l3_cache {
>  	unsigned indices;
> diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
> index 59554dca96ec..d9fceb697322 100644
> --- a/arch/x86/kernel/amd_nb.c
> +++ b/arch/x86/kernel/amd_nb.c
> @@ -179,7 +179,7 @@ int amd_get_subcaches(int cpu)
>  	return (mask >> (4 * cuid)) & 0xf;
>  }
>  
> -int amd_set_subcaches(int cpu, int mask)
> +int amd_set_subcaches(int cpu, unsigned long mask)
>  {
>  	static unsigned int reset, ban;
>  	struct amd_northbridge *nb = node_to_amd_nb(amd_get_nb_id(cpu));
> 

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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