linux-kernel - Re: [PATCH v3] net: asix: fix uninit value bugs

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Message-ID: <YRfjFr9GbcoJrycc@lunn.ch>
Date:   Sat, 14 Aug 2021 17:36:54 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Pavel Skripkin <paskripkin@...il.com>
Cc:     davem@...emloft.net, kuba@...nel.org, linux@...pel-privat.de,
        robert.foss@...labora.com, linux-usb@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzbot+a631ec9e717fb0423053@...kaller.appspotmail.com
Subject: Re: [PATCH v3] net: asix: fix uninit value bugs

On Sat, Aug 14, 2021 at 04:55:05PM +0300, Pavel Skripkin wrote:
> Syzbot reported uninit-value in asix_mdio_read(). The problem was in
> missing error handling. asix_read_cmd() should initialize passed stack
> variable smsr, but it can fail in some cases. Then while condidition
> checks possibly uninit smsr variable.
> 
> Since smsr is uninitialized stack variable, driver can misbehave,
> because smsr will be random in case of asix_read_cmd() failure.
> Fix it by adding error handling and just continue the loop instead of
> checking uninit value.
> 
> Also, same loop was used in 3 other functions. Fixed uninit value bug
> in them too.

Hi Pavel

Which suggests it might make sense to refactor the code to make a
helper? I will leave you to decide if you want to do that.

The code does looks correct now.

	Andrew