Re: [PATCH v2] scsi: 3w-9xxx: fix a missing-check bug

From: Martin K. Petersen
Date: Tue May 08 2018 - 01:34:24 EST


> In twa_chrdev_ioctl(), the ioctl driver command is firstly copied from the
> userspace pointer 'argp' and saved to the kernel object 'driver_command'.
> Then a security check is performed on the data buffer size indicated by
> 'driver_command', which is 'driver_command.buffer_length'. If the security
> check is passed, the entire ioctl command is copied again from the 'argp'
> pointer and saved to the kernel object 'tw_ioctl'. Then, various operations
> are performed on 'tw_ioctl' according to the 'cmd'. Given that the 'argp'
> pointer resides in userspace, a malicious userspace process can race to
> change the buffer size between the two copies. This way, the user can
> bypass the security check and inject invalid data buffer size. This can
> cause potential security issues in the following execution.
> This patch checks for capable(CAP_SYS_ADMIN) in twa_chrdev_open()t o avoid
> the above issues.

Applied patch 1 + 2 to 4.18/scsi-queue. Thank you.

Martin K. Petersen Oracle Linux Engineering