Messages in this thread | | | Date | Fri, 20 Apr 2018 07:58:22 +0200 | From | Uwe Kleine-König <> | Subject | Re: [v2 1/1] i2c: dev: prevent ZERO_SIZE_PTR deref in i2cdev_ioctl_rdwr() |
| |
Hello,
On Thu, Apr 19, 2018 at 08:01:46PM +0300, Alexander Popov wrote: > On 19.04.2018 16:49, Uwe Kleine-König wrote: > >> @@ -280,6 +280,7 @@ static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client, > >> */ > >> if (msgs[i].flags & I2C_M_RECV_LEN) { > >> if (!(msgs[i].flags & I2C_M_RD) || > >> + !msgs[i].len || > > > > I'd prefer > > > > msgs[i].len > 0 > > Excuse me, it will be wrong. We stop if len is 0 to avoid the following > ZERO_SIZE_PTR dereference.
right you are. I missed the negation.
> > here instead of > > > > !msgs[i].len > > I can change it to "msgs[i].len == 0". But is it really important? > > I've carefully tested the current version with the original repro. It works correct.
I don't doubt it, and the code generated is maybe even the same. The point I wanted to make is that
!len
is harder to read for a human than
len < 1
(or another suitable arithmetic expression). But feel free to disagree and keep the code as is.
Best regards Uwe
-- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |
| |