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From:   Peter Korsgaard <peter@korsgaard.com>
To:     Greg KH <gregkh@linuxfoundation.org>
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
References: <20231009-topic-dm9601_uninit_mdio_read-v2-1-f2fe39739b6c@gmail.com>
        <2023101036-fleshy-dude-aec0@gregkh>
Date:   Tue, 10 Oct 2023 08:19:48 +0200
In-Reply-To: <2023101036-fleshy-dude-aec0@gregkh> (Greg KH's message of "Tue,
        10 Oct 2023 08:00:14 +0200")
Message-ID: <87v8bfc83f.fsf@48ers.dk>
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>>>>> "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>

-- 
Bye, Peter Korsgaard