net/sched: unregister lockdep keys in qdisc_create/qdisc_alloc error path
Naresh and Eric report several errors (corrupted elements in the dynamic key hash list), when running tdc.py or syzbot. The error path of qdisc_alloc() and qdisc_create() frees the qdisc memory, but it forgets to unregister the lockdep key, thus causing use-after-free like the following one: ================================================================== BUG: KASAN: slab-use-after-free in lockdep_register_key+0x5f2/0x700 Read of size 8 at addr ffff88811236f2a8 by task ip/7925 CPU: 26 PID: 7925 Comm: ip Kdump: loaded Not tainted 6.9.0-rc2+ #648 Hardware name: Supermicro SYS-6027R-72RF/X9DRH-7TF/7F/iTF/iF, BIOS 3.0 07/26/2013 Call Trace: <TASK> dump_stack_lvl+0x7c/0xc0 print_report+0xc9/0x610 kasan_report+0x89/0xc0 lockdep_register_key+0x5f2/0x700 qdisc_alloc+0x21d/0xb60 qdisc_create_dflt+0x63/0x3c0 attach_one_default_qdisc.constprop.37+0x8e/0x170 dev_activate+0x4bd/0xc30 __dev_open+0x275/0x380 __dev_change_flags+0x3f1/0x570 dev_change_flags+0x7c/0x160 do_setlink+0x1ea1/0x34b0 __rtnl_newlink+0x8c9/0x1510 rtnl_newlink+0x61/0x90 rtnetlink_rcv_msg+0x2f0/0xbc0 netlink_rcv_skb+0x120/0x380 netlink_unicast+0x420/0x630 netlink_sendmsg+0x732/0xbc0 __sock_sendmsg+0x1ea/0x280 ____sys_sendmsg+0x5a9/0x990 ___sys_sendmsg+0xf1/0x180 __sys_sendmsg+0xd3/0x180 do_syscall_64+0x96/0x180 entry_SYSCALL_64_after_hwframe+0x71/0x79 RIP: 0033:0x7f9503f4fa07 Code: 0a 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b9 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 89 54 24 1c 48 89 74 24 10 RSP: 002b:00007fff6c729068 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 000000006630c681 RCX: 00007f9503f4fa07 RDX: 0000000000000000 RSI: 00007fff6c7290d0 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000078 R10: 000000000000009b R11: 0000000000000246 R12: 0000000000000001 R13: 00007fff6c729180 R14: 0000000000000000 R15: 000055bf67dd9040 </TASK> Allocated by task 7745: kasan_save_stack+0x1c/0x40 kasan_save_track+0x10/0x30 __kasan_kmalloc+0x7b/0x90 __kmalloc_node+0x1ff/0x460 qdisc_alloc+0xae/0xb60 qdisc_create+0xdd/0xfb0 tc_modify_qdisc+0x37e/0x1960 rtnetlink_rcv_msg+0x2f0/0xbc0 netlink_rcv_skb+0x120/0x380 netlink_unicast+0x420/0x630 netlink_sendmsg+0x732/0xbc0 __sock_sendmsg+0x1ea/0x280 ____sys_sendmsg+0x5a9/0x990 ___sys_sendmsg+0xf1/0x180 __sys_sendmsg+0xd3/0x180 do_syscall_64+0x96/0x180 entry_SYSCALL_64_after_hwframe+0x71/0x79 Freed by task 7745: kasan_save_stack+0x1c/0x40 kasan_save_track+0x10/0x30 kasan_save_free_info+0x36/0x60 __kasan_slab_free+0xfe/0x180 kfree+0x113/0x380 qdisc_create+0xafb/0xfb0 tc_modify_qdisc+0x37e/0x1960 rtnetlink_rcv_msg+0x2f0/0xbc0 netlink_rcv_skb+0x120/0x380 netlink_unicast+0x420/0x630 netlink_sendmsg+0x732/0xbc0 __sock_sendmsg+0x1ea/0x280 ____sys_sendmsg+0x5a9/0x990 ___sys_sendmsg+0xf1/0x180 __sys_sendmsg+0xd3/0x180 do_syscall_64+0x96/0x180 entry_SYSCALL_64_after_hwframe+0x71/0x79 Fix this ensuring that lockdep_unregister_key() is called before the qdisc struct is freed, also in the error path of qdisc_create() and qdisc_alloc(). Fixes: af0cb3fa ("net/sched: fix false lockdep warning on qdisc root lock") Reported-by:Linux Kernel Functional Testing <lkft@linaro.org> Closes: https://lore.kernel.org/netdev/20240429221706.1492418-1-naresh.kamboju@linaro.org/ Signed-off-by: