CVE-2026-53011net/sched: taprio: fix use-after-free in advance_sched() on schedule switch

Official description

In the Linux kernel, the following vulnerability has been resolved: net/sched: taprio: fix use-after-free in advance_sched() on schedule switch In advance_sched(), when should_change_schedules() returns true, switch_schedules() is called to promote the admin schedule to oper. switch_schedules() queues the old oper schedule for RCU freeing via call_rcu(), but 'next' still points into an entry of the old oper schedule. The subsequent 'next->end_time = end_time' and rcu_assign_pointer(q->current_entry, next) are use-after-free. Fix this by selecting 'next' from the new oper schedule immediately after switch_schedules(), and using its pre-calculated end_time. setup_first_end_time() sets the first entry's end_time to base_time + interval when the schedule is installed, so the value is already correct. The deleted 'end_time = sched_base_time(admin)' assignment was also harmful independently: it would overwrite the new first entry's pre-calculated end_time with just base_time.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/a8fc396519ef4f081bc545e88f61241728bb78d7
• https://git.kernel.org/stable/c/3471874578160a28c171a607fa069f24062634b8
• https://git.kernel.org/stable/c/7256996e1ef553716817f3bfd077c2f3b48b582f
• https://git.kernel.org/stable/c/eee072fe16c646190d33ae69c9983d8de1562bf8
• https://git.kernel.org/stable/c/1bd286fa3e21200133478ed523cc6a2788baf38a
• https://git.kernel.org/stable/c/b73235da5dde77ed1264f9767b62c28c9d71fd78
• https://git.kernel.org/stable/c/0e62171df8ed4804d00db088f17eed06468233fa
• https://git.kernel.org/stable/c/105425b1969c5affe532713cfac1c0b320d7ac2b