Re: [PATCH v4 sched_ext/for-7.3 08/40] sched_ext: Reject direct slice and dsq_vtime writes for cid-form schedulers

From: Tejun Heo

Date: Thu Jul 09 2026 - 18:28:46 EST


On Wed, 08 Jul 2026 21:41:20 +0000, sashiko-bot@xxxxxxxxxx wrote:
> - [Critical] bpf_scx_btf_struct_access_common permits BPF_WRITE to
> PTR_TO_BTF_ID | PTR_UNTRUSTED pointers, allowing arbitrary kernel memory
> writes.

This follows the same btf_struct_access contract as the other
implementations (tcp_ca, qdisc, hid): the callback validates the type and
confines the write to the one whitelisted field. Whatever the register's
trust flags, the store can only land on scx.disallow, a bool which only
gates SCHED_EXT admission - not a useful write primitive. No change.

Thanks.

--
tejun