Messages in this thread | | | Date | Thu, 19 Apr 2018 15:49:02 +0200 | From | Uwe Kleine-König <> | Subject | Re: [v2 1/1] i2c: dev: prevent ZERO_SIZE_PTR deref in i2cdev_ioctl_rdwr() |
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On Thu, Apr 19, 2018 at 03:29:22PM +0300, Alexander Popov wrote: > i2cdev_ioctl_rdwr() allocates i2c_msg.buf using memdup_user(), which > returns ZERO_SIZE_PTR if i2c_msg.len is zero. > > Currently i2cdev_ioctl_rdwr() always dereferences the buf pointer in case > of I2C_M_RD | I2C_M_RECV_LEN transfer. That causes a kernel oops in > case of zero len. > > Let's check the len against zero before dereferencing buf pointer. > > This issue was triggered by syzkaller. > > Signed-off-by: Alexander Popov <alex.popov@linux.com> > --- > drivers/i2c/i2c-dev.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c > index 036a03f..5790bc8 100644 > --- a/drivers/i2c/i2c-dev.c > +++ b/drivers/i2c/i2c-dev.c > @@ -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
here instead of
!msgs[i].len
because I can parse that more easily. Semantically the patch is fine and can have my
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> msgs[i].buf[0] < 1 || > msgs[i].len < msgs[i].buf[0] + > I2C_SMBUS_BLOCK_MAX) {
Best regards Uwe
-- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |
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