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BUG: KASAN: use-after-free in timer_is_static_object+0x7a/0x90 kernel/time/timer.c:620
Read of size 8 at addr ffff88805abfa380 by task syz-executor.3/28345

CPU: 1 PID: 28345 Comm: syz-executor.3 Not tainted 5.8.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 timer_is_static_object+0x7a/0x90 kernel/time/timer.c:620
 debug_object_assert_init lib/debugobjects.c:866 [inline]
 debug_object_assert_init+0x1df/0x2e0 lib/debugobjects.c:841
 debug_timer_assert_init kernel/time/timer.c:737 [inline]
 debug_assert_init kernel/time/timer.c:782 [inline]
 del_timer+0x6d/0x110 kernel/time/timer.c:1208
 try_to_grab_pending kernel/workqueue.c:1249 [inline]
 __cancel_work_timer+0x12d/0x700 kernel/workqueue.c:3092
 ceph_mdsc_stop fs/ceph/mds_client.c:4660 [inline]
 ceph_mdsc_destroy+0x50/0x140 fs/ceph/mds_client.c:4679
 destroy_fs_client+0x13/0x200 fs/ceph/super.c:720
 ceph_get_tree+0x9e5/0x1660 fs/ceph/super.c:1110
 vfs_get_tree+0x89/0x2f0 fs/super.c:1547
 do_new_mount fs/namespace.c:2875 [inline]
 do_mount+0x1592/0x1fe0 fs/namespace.c:3200
 __do_sys_mount fs/namespace.c:3410 [inline]
 __se_sys_mount fs/namespace.c:3387 [inline]
 __x64_sys_mount+0x18f/0x230 fs/namespace.c:3387
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45cc79
Code: 2d b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 fb b5 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fc8dbcfec78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000020440 RCX: 000000000045cc79
RDX: 0000000020000140 RSI: 00000000200000c0 RDI: 00000000200005c0
RBP: 000000000078bf50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c
R13: 00007ffe7b2a4b4f R14: 00007fc8dbcff9c0 R15: 000000000078bf0c

Allocated by task 28345:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
 kmem_cache_alloc_trace+0x14f/0x2d0 mm/slab.c:3551
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:669 [inline]
 ceph_mdsc_init+0x47/0xf10 fs/ceph/mds_client.c:4351
 ceph_get_tree+0x4fe/0x1660 fs/ceph/super.c:1063
 vfs_get_tree+0x89/0x2f0 fs/super.c:1547
 do_new_mount fs/namespace.c:2875 [inline]
 do_mount+0x1592/0x1fe0 fs/namespace.c:3200
 __do_sys_mount fs/namespace.c:3410 [inline]
 __se_sys_mount fs/namespace.c:3387 [inline]
 __x64_sys_mount+0x18f/0x230 fs/namespace.c:3387
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 28345:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 kasan_set_free_info mm/kasan/common.c:316 [inline]
 __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x103/0x2c0 mm/slab.c:3757
 ceph_mdsc_init+0xc64/0xf10 fs/ceph/mds_client.c:4422
 ceph_get_tree+0x4fe/0x1660 fs/ceph/super.c:1063
 vfs_get_tree+0x89/0x2f0 fs/super.c:1547
 do_new_mount fs/namespace.c:2875 [inline]
 do_mount+0x1592/0x1fe0 fs/namespace.c:3200
 __do_sys_mount fs/namespace.c:3410 [inline]
 __se_sys_mount fs/namespace.c:3387 [inline]
 __x64_sys_mount+0x18f/0x230 fs/namespace.c:3387
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff88805abfa000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 896 bytes inside of
 4096-byte region [ffff88805abfa000, ffff88805abfb000)
The buggy address belongs to the page:
page:ffffea00016afe80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea00016afe80 order:1 compound_mapcount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea00016afe08 ffffea00019ca208 ffff8880aa002000
raw: 0000000000000000 ffff88805abfa000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88805abfa280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805abfa300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88805abfa380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88805abfa400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805abfa480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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