Re: [syzbot] [net?] KASAN: slab-use-after-free Read in advance_sched

[Hillf Danton]

On Fri, 23 Feb 2024 01:29:17 -0800
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    9abbc24128bc Merge branch 'for-next/core' into for-kernelci
> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10a70158180000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git  for-kernelci

--- x/net/sched/sch_taprio.c
+++ y/net/sched/sch_taprio.c
@@ -1984,6 +1984,7 @@ static int taprio_change(struct Qdisc *s
 		/* Protects against advance_sched() */
 		spin_lock_irqsave(&q->current_entry_lock, flags);
 
+		admin = rtnl_dereference(q->admin_sched);
 		taprio_start_sched(sch, start, new_admin);
 
 		rcu_assign_pointer(q->admin_sched, new_admin);
--