Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH 2/2] time/namespace: Forbid timens page faults under kthread_use_mm() | Date | Wed, 30 Nov 2022 01:09:36 +0100 |
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On Tue, Nov 29 2022 at 23:34, Jann Horn wrote: > On Tue, Nov 29, 2022 at 11:28 PM Jann Horn <jannh@google.com> wrote: >> That said, I haven't actually tried it. But I don't think there's >> anything in the page fault handling path that distinguishes between >> copy_from_user() faults in kthread context and other userspace faults >> in a relevant way? > > Ah, but I guess even if this can happen, it's not actually as bad as I > thought, since kthreads are in init_time_ns, and init_time_ns doesn't > have a ->vvar_page, so this isn't going to lead to anything terrible > like page UAF, and it's just a garbage-in-garbage-out scenario.
True, but catching the kthread -> fault (vvar/vdso page) scenario definitely has a value.
Thanks,
tglx
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