linux-kernel - Re: [PATCH] net: bnx2x: fix variable dereferenced before check

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Message-ID: <018ada52-3e9b-8909-2346-ea2ce1d817fa@gmail.com>
Date:   Thu, 18 Nov 2021 12:00:21 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     Johan Hovold <johan@...nel.org>,
        Dan Carpenter <dan.carpenter@...cle.com>
Cc:     aelior@...vell.com, skalluru@...vell.com,
        GR-everest-linux-l2@...vell.com, davem@...emloft.net,
        kuba@...nel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: bnx2x: fix variable dereferenced before check

On 11/18/21 11:51, Johan Hovold wrote:
> [ Adding Dan. ]
> 
> On Sun, Nov 14, 2021 at 01:36:36AM +0300, Pavel Skripkin wrote:
>> Smatch says:
>> 	bnx2x_init_ops.h:640 bnx2x_ilt_client_mem_op()
>> 	warn: variable dereferenced before check 'ilt' (see line 638)
>> 
>> Move ilt_cli variable initialization _after_ ilt validation, because
>> it's unsafe to deref the pointer before validation check.
> 
> It seems smatch is confused here. There is no dereference happening
> until after the check, we're just determining the address when
> initialising ilt_cli.
> 
> I know this has been applied, and the change itself is fine, but the
> patch description is wrong and the Fixes tag is unwarranted.
>   

I agree. I came up with same thing after the patch has been applied. I 
thought about a revert, but seems it's not necessary, since there is no 
function change.

I should check smatch warnings more carefully next time, can't say why I 
didn't notice it before sending :(

thanks



With regards,
Pavel Skripkin