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BUG: KASAN: use-after-free in afs_manage_cell+0xbd6/0x1540 fs/afs/cell.c:674
Write of size 4 at addr ffff88806e5898b8 by task kworker/0:4/14628

CPU: 0 PID: 14628 Comm: kworker/0:4 Not tainted 5.9.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: afs afs_manage_cell
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d6/0x29e lib/dump_stack.c:118
 print_address_description+0x66/0x620 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report+0x132/0x1d0 mm/kasan/report.c:530
 afs_manage_cell+0xbd6/0x1540 fs/afs/cell.c:674
 process_one_work+0x789/0xfc0 kernel/workqueue.c:2269
 worker_thread+0xaa4/0x1460 kernel/workqueue.c:2415
 kthread+0x37e/0x3a0 drivers/block/aoe/aoecmd.c:1234
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Allocated by task 19088:
 kasan_save_stack mm/kasan/common.c:48 [inline]
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc+0x100/0x130 mm/kasan/common.c:461
 kmem_cache_alloc_trace+0x1e4/0x2e0 mm/slab.c:3550
 kmalloc include/linux/slab.h:554 [inline]
 kzalloc include/linux/slab.h:666 [inline]
 afs_alloc_cell fs/afs/cell.c:151 [inline]
 afs_lookup_cell+0x4ab/0x14d0 fs/afs/cell.c:262
 afs_parse_source fs/afs/super.c:290 [inline]
 afs_parse_param+0x526/0x790 fs/afs/super.c:326
 vfs_parse_fs_param+0x1e5/0x460 fs/fs_context.c:117
 vfs_parse_fs_string fs/fs_context.c:161 [inline]
 generic_parse_monolithic+0x230/0x350 fs/fs_context.c:201
 do_new_mount fs/namespace.c:2871 [inline]
 path_mount+0x176c/0x29e0 fs/namespace.c:3192
 do_mount fs/namespace.c:3205 [inline]
 __do_sys_mount fs/namespace.c:3413 [inline]
 __se_sys_mount+0x126/0x180 fs/namespace.c:3390
 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 19084:
 kasan_save_stack mm/kasan/common.c:48 [inline]
 kasan_set_track+0x3d/0x70 mm/kasan/common.c:56
 kasan_set_free_info+0x17/0x30 mm/kasan/generic.c:355
 __kasan_slab_free+0xdd/0x110 mm/kasan/common.c:422
 __cache_free mm/slab.c:3418 [inline]
 kfree+0x113/0x200 mm/slab.c:3756
 rcu_do_batch kernel/rcu/tree.c:2428 [inline]
 rcu_core+0x79b/0x1130 kernel/rcu/tree.c:2656
 __do_softirq+0x256/0x6d5 kernel/softirq.c:298

Last call_rcu():
 kasan_save_stack+0x27/0x50 mm/kasan/common.c:48
 kasan_record_aux_stack+0x7b/0xb0 mm/kasan/generic.c:346
 __call_rcu kernel/rcu/tree.c:2894 [inline]
 call_rcu+0x141/0x830 kernel/rcu/tree.c:2968
 afs_manage_cell+0xd7d/0x1540 fs/afs/cell.c:751
 process_one_work+0x789/0xfc0 kernel/workqueue.c:2269
 worker_thread+0xaa4/0x1460 kernel/workqueue.c:2415
 kthread+0x37e/0x3a0 drivers/block/aoe/aoecmd.c:1234
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Second to last call_rcu():
 kasan_save_stack+0x27/0x50 mm/kasan/common.c:48
 kasan_record_aux_stack+0x7b/0xb0 mm/kasan/generic.c:346
 __call_rcu kernel/rcu/tree.c:2894 [inline]
 call_rcu+0x141/0x830 kernel/rcu/tree.c:2968
 taprio_destroy+0x44c/0x640 net/sched/sch_taprio.c:1609
 qdisc_create+0xfc4/0x1410 net/sched/sch_api.c:1312
 tc_modify_qdisc+0x962/0x1d90 net/sched/sch_api.c:1662
 rtnetlink_rcv_msg+0x889/0xd40 net/core/rtnetlink.c:5563
 netlink_rcv_skb+0x190/0x3a0 net/netlink/af_netlink.c:2470
 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
 netlink_unicast+0x786/0x940 net/netlink/af_netlink.c:1330
 netlink_sendmsg+0xa57/0xd70 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg net/socket.c:671 [inline]
 ____sys_sendmsg+0x519/0x800 net/socket.c:2353
 ___sys_sendmsg net/socket.c:2407 [inline]
 __sys_sendmsg+0x2b1/0x360 net/socket.c:2440
 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff88806e589800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 184 bytes inside of
 1024-byte region [ffff88806e589800, ffff88806e589c00)
The buggy address belongs to the page:
page:000000007dfd4810 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x6e589
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00022825c8 ffffea00013b5088 ffff8880aa440700
raw: 0000000000000000 ffff88806e589000 0000000100000002 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88806e589780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88806e589800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88806e589880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff88806e589900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88806e589980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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