linux-kernel - Re: [PATCH][next] soc: xilinx: vcu: remove deadcode on null divider check

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20210211073156.GB30300@pengutronix.de>
Date:   Thu, 11 Feb 2021 08:31:56 +0100
From:   Michael Tretter <m.tretter@...gutronix.de>
To:     Colin King <colin.king@...onical.com>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Michal Simek <michal.simek@...inx.com>,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] soc: xilinx: vcu: remove deadcode on null divider
 check

On Wed, 10 Feb 2021 18:49:38 +0000, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> The pointer 'divider' has previously been null checked followed by
> a return, hence the subsequent null check is redundant deadcode
> that can be removed.  Clean up the code and remove it.
> 
> Fixes: 9c789deea206 ("soc: xilinx: vcu: implement clock provider for output clocks")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/clk/xilinx/xlnx_vcu.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/drivers/clk/xilinx/xlnx_vcu.c b/drivers/clk/xilinx/xlnx_vcu.c
> index d66b1315114e..607936d7a413 100644
> --- a/drivers/clk/xilinx/xlnx_vcu.c
> +++ b/drivers/clk/xilinx/xlnx_vcu.c
> @@ -512,9 +512,6 @@ static void xvcu_clk_hw_unregister_leaf(struct clk_hw *hw)
>  
>  	mux = clk_hw_get_parent(divider);
>  	clk_hw_unregister_mux(mux);
> -	if (!divider)
> -		return;
> -
>  	clk_hw_unregister_divider(divider);

Thanks for pointing this out. There is actually a different bug there.

There should have been a check for !mux before unregistering the mux:

	mux = clk_hw_get_parent(divider);
	clk_hw_unregister_divider(divider);
	if (!mux)
		return;

	clk_hw_unregister_mux(mux);

Michael

>  }
>  
> -- 
> 2.30.0
> 
>