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@xxxxxxxxx>
> ---
> 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@xxxxxxxxxxxxxx>
> 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/ |
