linux-kernel - Re: [PATCH] kernel/sysctl.c: drop unneeded assignment in proc_do_large

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Date:   Mon, 5 Oct 2020 14:05:11 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Sudip Mukherjee <sudipm.mukherjee@...il.com>
Cc:     Luis Chamberlain <mcgrof@...nel.org>,
        Iurii Zaikin <yzaikin@...gle.com>,
        linux-kernel@...r.kernel.org, linux-safety@...ts.elisa.tech,
        linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] kernel/sysctl.c: drop unneeded assignment in
 proc_do_large_bitmap()

On Mon, Oct 05, 2020 at 09:37:49PM +0100, Sudip Mukherjee wrote:
> The variable 'first' is assigned 0 inside the while loop in the if block
> but it is not used in the if block and is only used in the else block.
> So, remove the unneeded assignment.

True, but in this case, please move the definition of "first" into the
else block so it in only in scope there.

Thanks!

-Kees

> 
> Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@...il.com>
> ---
> 
> The resultant binary stayed same after this change. Verified with
> md5sum which remained same with and without this change.
> 
> $ md5sum kernel/sysctl.o 
> e9e97adbfd3f0b32f83dd35d100c0e4e  kernel/sysctl.o
> 
>  kernel/sysctl.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index ce75c67572b9..b51ebfd1ba6e 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -1508,7 +1508,6 @@ int proc_do_large_bitmap(struct ctl_table *table, int write,
>  			}
>  
>  			bitmap_set(tmp_bitmap, val_a, val_b - val_a + 1);
> -			first = 0;
>  			proc_skip_char(&p, &left, '\n');
>  		}
>  		left += skipped;
> -- 
> 2.11.0
> 

-- 
Kees Cook