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Date:   Tue, 10 Oct 2023 08:33:35 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Peter Korsgaard <peter@korsgaard.com>
Cc:     Javier Carrasco <javier.carrasco.cruz@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        syzbot+1f53a30781af65d2c955@syzkaller.appspotmail.com,
        netdev@vger.kernel.org, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] net: usb: dm9601: fix uninitialized variable use in
 dm9601_mdio_read
Message-ID: <2023101018-venomous-uncured-47cf@gregkh>
References: <20231009-topic-dm9601_uninit_mdio_read-v2-1-f2fe39739b6c@gmail.com>
 <2023101036-fleshy-dude-aec0@gregkh>
 <87v8bfc83f.fsf@48ers.dk>
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On Tue, Oct 10, 2023 at 08:19:48AM +0200, Peter Korsgaard wrote:
> >>>>> "Greg" == Greg KH <gregkh@linuxfoundation.org> writes:
> 
>  > On Tue, Oct 10, 2023 at 12:26:14AM +0200, Javier Carrasco wrote:
>  >> syzbot has found an uninit-value bug triggered by the dm9601 driver [1].
>  >> 
>  >> This error happens because the variable res is not updated if the call
>  >> to dm_read_shared_word returns an error. In this particular case -EPROTO
>  >> was returned and res stayed uninitialized.
>  >> 
>  >> This can be avoided by checking the return value of dm_read_shared_word
>  >> and propagating the error if the read operation failed.
>  >> 
>  >> [1] https://syzkaller.appspot.com/bug?extid=1f53a30781af65d2c955
>  >> 
>  >> Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
>  >> Reported-and-tested-by: syzbot+1f53a30781af65d2c955@syzkaller.appspotmail.com
>  >> ---
>  >> Changes in v2:
>  >> - Remove unnecessary 'err == 0' case
>  >> - Link to v1: https://lore.kernel.org/r/20231009-topic-dm9601_uninit_mdio_read-v1-1-d4d775e24e3b@gmail.com
>  >> ---
>  >> drivers/net/usb/dm9601.c | 7 ++++++-
>  >> 1 file changed, 6 insertions(+), 1 deletion(-)
> 
>  > What commit id does this fix?
> 
> It has been there since the beginning, so:
> 
> Fixes: d0374f4f9c35cdfbee0 ("USB: Davicom DM9601 usbnet driver")
> 
> Acked-by: Peter Korsgaard <peter@korsgaard.com>

Great, can someone add a cc: stable@ tag for this too please?

thanks,

greg k-h