linux-kernel - Re: [PATCH] net: usb: Fix uninit-was-stored issue in asix_read_phy

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Date:   Fri, 28 Aug 2020 16:36:22 +0530
From:   Himadri Pandya <himadrispandya@...il.com>
To:     Sergei Shtylyov <sergei.shtylyov@...il.com>
Cc:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        USB list <linux-usb@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        Greg KH <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] net: usb: Fix uninit-was-stored issue in asix_read_phy_addr()

On Thu, Aug 27, 2020 at 1:28 PM Sergei Shtylyov
<sergei.shtylyov@...il.com> wrote:
>
> Hello!
>
> On 27.08.2020 9:53, Himadri Pandya wrote:
>
> > The buffer size is 2 Bytes and we expect to receive the same amount of
> > data. But sometimes we receive less data and run into uninit-was-stored
> > issue upon read. Hence modify the error check on the return value to match
> > with the buffer size as a prevention.
> >
> > Reported-and-tested by: syzbot+a7e220df5a81d1ab400e@...kaller.appspotmail.com
> > Signed-off-by: Himadri Pandya <himadrispandya@...il.com>
> > ---
> >   drivers/net/usb/asix_common.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/usb/asix_common.c b/drivers/net/usb/asix_common.c
> > index e39f41efda3e..7bc6e8f856fe 100644
> > --- a/drivers/net/usb/asix_common.c
> > +++ b/drivers/net/usb/asix_common.c
> > @@ -296,7 +296,7 @@ int asix_read_phy_addr(struct usbnet *dev, int internal)
> >
> >       netdev_dbg(dev->net, "asix_get_phy_addr()\n");
> >
> > -     if (ret < 0) {
> > +     if (ret < 2) {
> >               netdev_err(dev->net, "Error reading PHYID register: %02x\n", ret);
>
>     Hm... printing possibly negative values as hex?
>

Yeah. That's odd! Fixing it.

Thanks,
Himadri

> [...]
>
> MBR, Sergei