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Date:   Fri, 20 Mar 2020 15:57:48 +0100
From:   Wolfram Sang <wsa@the-dreams.de>
To:     Dan Carpenter <dan.carpenter@oracle.com>,
        Jean Delvare <jdelvare@suse.de>,
        Daniel Kurtz <djkurtz@chromium.org>
Cc:     linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org,
        syzbot <syzbot+ed71512d469895b5b34e@syzkaller.appspotmail.com>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Jarkko Nikula <jarkko.nikula@linux.intel.com>
Subject: Re: [PATCH] i2c: i801: Fix memory corruption in i801_isr_byte_done()
Message-ID: <20200320145748.GD1282@ninjato>
References: <0000000000009586b2059c13c7e1@google.com>
 <20200114073406.qaq3hbrhtx76fkes@kili.mountain>
 <20200222124523.GI1716@kunai>
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On Sat, Feb 22, 2020 at 01:45:23PM +0100, Wolfram Sang wrote:
> On Tue, Jan 14, 2020 at 10:34:06AM +0300, Dan Carpenter wrote:
> > Assigning "priv->data[-1] =3D priv->len;" obviously doesn't make sense.
> > What it does is it ends up corrupting the last byte of priv->len so
> > priv->len becomes a very high number.
> >=20
> > Reported-by: syzbot+ed71512d469895b5b34e@syzkaller.appspotmail.com
> > Fixes: d3ff6ce40031 ("i2c-i801: Enable IRQ for byte_by_byte transaction=
s")
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > ---
>=20
> Daniel, Jean: what do you think?
> Also, adding Jarkko to CC who works a lot with this driver...

Ping. Adding more people...

>=20
> > Untested.
> >=20
> >  drivers/i2c/busses/i2c-i801.c | 1 -
> >  1 file changed, 1 deletion(-)
> >=20
> > diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i80=
1.c
> > index f5e69fe56532..420d8025901e 100644
> > --- a/drivers/i2c/busses/i2c-i801.c
> > +++ b/drivers/i2c/busses/i2c-i801.c
> > @@ -584,7 +584,6 @@ static void i801_isr_byte_done(struct i801_priv *pr=
iv)
> >  					"SMBus block read size is %d\n",
> >  					priv->len);
> >  			}
> > -			priv->data[-1] =3D priv->len;
> >  		}
> > =20
> >  		/* Read next byte */
> > --=20
> > 2.11.0
> >=20


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