linux-kernel - Re: [PATCH] staging: lustre: lustre: obdclass: lprocfs_status.c: Fix for possible null pointer dereference

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Date:	Sun, 14 Dec 2014 14:39:53 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
Cc:	Oleg Drokin <oleg.drokin@...el.com>,
	Andreas Dilger <andreas.dilger@...el.com>,
	Julia Lawall <Julia.Lawall@...6.fr>,
	Greg Donald <gdonald@...il.com>,
	"John L. Hammond" <john.hammond@...el.com>,
	Andriy Skulysh <Andriy_Skulysh@...atex.com>,
	Fabian Frederick <fabf@...net.be>,
	James Simmons <uja.ornl@...il.com>, HPDD-discuss@...ts.01.org,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: lustre: lustre: obdclass: lprocfs_status.c: Fix
 for possible null pointer dereference

On Sun, Dec 14, 2014 at 11:36:22PM +0100, Rickard Strandqvist wrote:
> There is otherwise a risk of a possible null pointer dereference.
> 
> Was largely found by using a static code analysis program called cppcheck.
> 
> Signed-off-by: Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
> ---
>  .../lustre/lustre/obdclass/lprocfs_status.c        |   20 +++++++++-----------
>  1 file changed, 9 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
> index 61e04af..4a7891a 100644
> --- a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
> +++ b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
> @@ -1897,17 +1897,15 @@ int lprocfs_write_frac_u64_helper(const char *buffer, unsigned long count,
>  	}
>  
>  	units = 1;
> -	switch (*end) {
> -	case 'p': case 'P':
> -		units <<= 10;
> -	case 't': case 'T':
> -		units <<= 10;
> -	case 'g': case 'G':
> -		units <<= 10;
> -	case 'm': case 'M':
> -		units <<= 10;
> -	case 'k': case 'K':
> -		units <<= 10;
> +	if (end) {
> +		switch (*end) {
> +		case 'p': case 'P':
> +		case 't': case 'T':
> +		case 'g': case 'G':
> +		case 'm': case 'M':
> +		case 'k': case 'K':
> +			units <<= 10;
> +		}

You know you just changed the logic in the code, right?

Why?  Have you tested this?

greg k-h
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