Re: [RFC PATCH for 4.18 1/2] rseq: validate rseq_cs fields are < TASK_SIZE
From: Mathieu Desnoyers
Date: Mon Jul 02 2018 - 15:00:25 EST
----- On Jul 2, 2018, at 1:11 PM, Andy Lutomirski luto@xxxxxxxxxxxxxx wrote:
>
> But I think that the limited solution of changing
> instruction_pointer_set() really is a sufficient
> architecture-dependent change to fully solve your problem.
So let me recap with the changes I gather for 4.18 and 4.19:
4.18:
* Change struct rseq_cs field types from LINUX_FIELD_u32_u64() to __u64 in
uapi/linux/rseq.h,
* Compare rseq->rseq_cs->abort_ip with TASK_SIZE before using it. Kill offending
process if its value is over TASK_SIZE,
* Explicitly check that padding of rseq->rseq_cs is zero on 32-bit kernels
(#ifndef __LP64__).
4.19:
* Introduce instruction_pointer_set() with input validation, use it when setting
IP to abort_ip in rseq. This replaces the comparison of abort_ip with TASK_SIZE.
Is that consistent with what you have in mind ?
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com