Messages in this thread | | | Date | Tue, 21 Jul 2020 07:35:42 +0200 | From | Christoph Hellwig <> | Subject | Re: [PATCH 1/6] syscalls: use uaccess_kernel in addr_limit_user_check |
| |
On Mon, Jul 20, 2020 at 10:30:30PM -0700, Guenter Roeck wrote: > Guess I lost it somewhere. Are you saying the check was wrong all along > and your patch fixed it ?
Oh, it is a little complicated.
Normally we have two address space limits, KERNEL_DS and USER_DS, and they are supposed to be different. armnommu and m68k define them to the same value for no good reason. That leads to:
uaccess_kernel always returning true as it does a positive check agains KERNEL_DS, which disables a bunch of drivers like sg and rdma, and could also lead to really strange and probably broken results in a few places.
It also leads to the SIGKILL in addr_limit_user_check never triggering due to the negatіve check, which is ok as the limits never are different.
| |