linux-kernel - Re: [syzbot] [net?] general protection fault in qdisc_tree_reduce

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Message-ID: <20250704072511.2387-1-hdanton@sina.com>
Date: Fri,  4 Jul 2025 15:25:03 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+1261670bbdefc5485a06@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [net?] general protection fault in qdisc_tree_reduce_backlog

> Date: Thu, 03 Jul 2025 22:20:37 -0700
> syzbot found the following issue on:
> 
> HEAD commit:    bd475eeaaf3c Merge branch '200GbE' of git://git.kernel.org..
> git tree:       net
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=12f0b3d4580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=36b0e72cad5298f8
> dashboard link: https://syzkaller.appspot.com/bug?extid=1261670bbdefc5485a06
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=164d8c8c580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14839ebc580000

#syz test

--- x/net/sched/sch_api.c
+++ y/net/sched/sch_api.c
@@ -803,7 +803,7 @@ void qdisc_tree_reduce_backlog(struct Qd
 			break;
 		}
 		cops = sch->ops->cl_ops;
-		if (notify && cops->qlen_notify) {
+		if (notify && cops && cops->qlen_notify) {
 			/* Note that qlen_notify must be idempotent as it may get called
 			 * multiple times.
 			 */
--