==================================================================
BUG: KASAN: use-after-free in hlist_add_head include/linux/list.h:814 [inline]
BUG: KASAN: use-after-free in enqueue_timer+0xb7/0x300 kernel/time/timer.c:541
Write of size 8 at addr ffff8881e1a4f1c8 by task syz.4.89/648

CPU: 1 PID: 648 Comm: syz.4.89 Not tainted 5.4.290-syzkaller-00002-g41adfeb3d639 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d8/0x241 lib/dump_stack.c:118
 print_address_description+0x8c/0x600 mm/kasan/report.c:384
 __kasan_report+0xf3/0x120 mm/kasan/report.c:516
 kasan_report+0x30/0x60 mm/kasan/common.c:653
 hlist_add_head include/linux/list.h:814 [inline]
 enqueue_timer+0xb7/0x300 kernel/time/timer.c:541
 __internal_add_timer kernel/time/timer.c:554 [inline]
 internal_add_timer+0x240/0x430 kernel/time/timer.c:604
 __mod_timer+0x6f1/0x13e0 kernel/time/timer.c:1065
 call_timer_fn+0x36/0x390 kernel/time/timer.c:1448
 expire_timers kernel/time/timer.c:1493 [inline]
 __run_timers+0x879/0xbe0 kernel/time/timer.c:1817
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1830
 __do_softirq+0x23b/0x6b7 kernel/softirq.c:292
 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1086
 </IRQ>
 do_softirq+0x121/0x160 kernel/softirq.c:337
 __local_bh_enable_ip+0x6a/0x70 kernel/softirq.c:189
 rcu_read_unlock_bh include/linux/rcupdate.h:739 [inline]
 __dev_queue_xmit+0x1532/0x2790 net/core/dev.c:3848
 __bpf_tx_skb net/core/filter.c:2063 [inline]
 __bpf_redirect_no_mac net/core/filter.c:2097 [inline]
 __bpf_redirect+0x78f/0xe20 net/core/filter.c:2120
 ____bpf_clone_redirect net/core/filter.c:2151 [inline]
 bpf_clone_redirect+0x249/0x350 net/core/filter.c:2123
 bpf_prog_973cd02a7a0e8181+0xf32/0x1000
 bpf_call_func include/linux/filter.h:627 [inline]
 bpf_test_run+0x2ae/0x6c0 net/bpf/test_run.c:44
 bpf_prog_test_run_skb+0x73c/0xf00 net/bpf/test_run.c:311
 bpf_prog_test_run kernel/bpf/syscall.c:2124 [inline]
 __do_sys_bpf kernel/bpf/syscall.c:2909 [inline]
 __se_sys_bpf+0x2e37/0xbcb0 kernel/bpf/syscall.c:2849
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1
RIP: 0033:0x7f8f7ef4d169
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8f7d5b7038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f8f7f165fa0 RCX: 00007f8f7ef4d169
RDX: 000000000000002c RSI: 0000200000000080 RDI: 000000000000000a
RBP: 00007f8f7efce2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f8f7f165fa0 R15: 00007ffe7f9431d8

Allocated by task 352:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 __kasan_kmalloc+0x171/0x210 mm/kasan/common.c:529
 slab_post_alloc_hook mm/slab.h:584 [inline]
 slab_alloc_node mm/slub.c:2829 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 kmem_cache_alloc+0xd9/0x250 mm/slub.c:2842
 shmem_alloc_inode+0x16/0x30 mm/shmem.c:3719
 alloc_inode fs/inode.c:231 [inline]
 new_inode_pseudo+0x60/0x210 fs/inode.c:966
 new_inode+0x25/0x1d0 fs/inode.c:995
 shmem_get_inode+0x10b/0x620 mm/shmem.c:2252
 shmem_mknod+0x54/0x1a0 mm/shmem.c:2844
 lookup_open fs/namei.c:3379 [inline]
 do_last fs/namei.c:3471 [inline]
 path_openat+0x184a/0x34b0 fs/namei.c:3683
 do_filp_open+0x20b/0x450 fs/namei.c:3713
 do_sys_open+0x39c/0x810 fs/open.c:1123
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

Freed by task 17:
 save_stack mm/kasan/common.c:70 [inline]
 set_track mm/kasan/common.c:78 [inline]
 kasan_set_free_info mm/kasan/common.c:345 [inline]
 __kasan_slab_free+0x1b5/0x270 mm/kasan/common.c:487
 slab_free_hook mm/slub.c:1455 [inline]
 slab_free_freelist_hook mm/slub.c:1494 [inline]
 slab_free mm/slub.c:3080 [inline]
 kmem_cache_free+0x10b/0x2c0 mm/slub.c:3096
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch+0x492/0xa00 kernel/rcu/tree.c:2167
 rcu_core+0x4c8/0xcb0 kernel/rcu/tree.c:2387
 __do_softirq+0x23b/0x6b7 kernel/softirq.c:292

The buggy address belongs to the object at ffff8881e1a4f090
 which belongs to the cache shmem_inode_cache of size 760
The buggy address is located 312 bytes inside of
 760-byte region [ffff8881e1a4f090, ffff8881e1a4f388)
The buggy address belongs to the page:
page:ffffea0007869300 refcount:1 mapcount:0 mapping:ffff8881f5cff900 index:0x0 compound_mapcount: 0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5cff900
raw: 0000000000000000 0000000000120012 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL)
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook mm/page_alloc.c:2165 [inline]
 prep_new_page+0x18f/0x370 mm/page_alloc.c:2171
 get_page_from_freelist+0x2d13/0x2d90 mm/page_alloc.c:3794
 __alloc_pages_nodemask+0x393/0x840 mm/page_alloc.c:4893
 alloc_slab_page+0x39/0x3c0 mm/slub.c:343
 allocate_slab mm/slub.c:1683 [inline]
 new_slab+0x97/0x440 mm/slub.c:1749
 new_slab_objects mm/slub.c:2505 [inline]
 ___slab_alloc+0x2fe/0x490 mm/slub.c:2667
 __slab_alloc+0x62/0xa0 mm/slub.c:2707
 slab_alloc_node mm/slub.c:2792 [inline]
 slab_alloc mm/slub.c:2837 [inline]
 kmem_cache_alloc+0x109/0x250 mm/slub.c:2842
 shmem_alloc_inode+0x16/0x30 mm/shmem.c:3719
 alloc_inode fs/inode.c:231 [inline]
 new_inode_pseudo+0x60/0x210 fs/inode.c:966
 new_inode+0x25/0x1d0 fs/inode.c:995
 shmem_get_inode+0x10b/0x620 mm/shmem.c:2252
 shmem_symlink+0x118/0x5f0 mm/shmem.c:3068
 vfs_symlink+0x36c/0x500 fs/namei.c:4276
 do_symlinkat+0x19b/0x400 fs/namei.c:4303
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1176 [inline]
 __free_pages_ok+0x847/0x950 mm/page_alloc.c:1438
 free_the_page mm/page_alloc.c:4955 [inline]
 __free_pages+0x91/0x140 mm/page_alloc.c:4961
 device_release+0x6b/0x190 drivers/base/core.c:1776
 kobject_cleanup lib/kobject.c:716 [inline]
 kobject_release lib/kobject.c:747 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1e6/0x2f0 lib/kobject.c:764
 netdev_run_todo+0xc44/0xdf0 net/core/dev.c:9488
 tun_detach drivers/net/tun.c:766 [inline]
 tun_chr_close+0xc1/0x130 drivers/net/tun.c:3563
 __fput+0x262/0x680 fs/file_table.c:281
 task_work_run+0x140/0x170 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x190/0x1a0 arch/x86/entry/common.c:163
 prepare_exit_to_usermode+0x199/0x200 arch/x86/entry/common.c:194
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

Memory state around the buggy address:
 ffff8881e1a4f080: fc fc fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881e1a4f100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881e1a4f180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff8881e1a4f200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881e1a4f280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 1dfe96067 P4D 1dfe96067 PUD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 648 Comm: syz.4.89 Tainted: G    B             5.4.290-syzkaller-00002-g41adfeb3d639 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffff8881f6f09d78 EFLAGS: 00010002
RAX: ffffffff8154e8ca RBX: 0000000000000102 RCX: ffff8881dee49f80
RDX: 0000000000000102 RSI: 0000000000000000 RDI: ffff8881e1a4f1c0
RBP: ffff8881f6f09f28 R08: ffffffff8154e50e R09: 0000000000000003
R10: ffffffffffffffff R11: dffffc0000000001 R12: 00000000ffff98e8
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881e1a4f1c0
FS:  00007f8f7d5b76c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001dcd08000 CR4: 00000000003406a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 call_timer_fn+0x36/0x390 kernel/time/timer.c:1448
 expire_timers kernel/time/timer.c:1488 [inline]
 __run_timers+0x8a5/0xbe0 kernel/time/timer.c:1817
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1830
 __do_softirq+0x23b/0x6b7 kernel/softirq.c:292
 do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:1086
 </IRQ>
 do_softirq+0x121/0x160 kernel/softirq.c:337
 __local_bh_enable_ip+0x6a/0x70 kernel/softirq.c:189
 rcu_read_unlock_bh include/linux/rcupdate.h:739 [inline]
 __dev_queue_xmit+0x1532/0x2790 net/core/dev.c:3848
 __bpf_tx_skb net/core/filter.c:2063 [inline]
 __bpf_redirect_no_mac net/core/filter.c:2097 [inline]
 __bpf_redirect+0x78f/0xe20 net/core/filter.c:2120
 ____bpf_clone_redirect net/core/filter.c:2151 [inline]
 bpf_clone_redirect+0x249/0x350 net/core/filter.c:2123
 bpf_prog_973cd02a7a0e8181+0xf32/0x1000
 bpf_call_func include/linux/filter.h:627 [inline]
 bpf_test_run+0x2ae/0x6c0 net/bpf/test_run.c:44
 bpf_prog_test_run_skb+0x73c/0xf00 net/bpf/test_run.c:311
 bpf_prog_test_run kernel/bpf/syscall.c:2124 [inline]
 __do_sys_bpf kernel/bpf/syscall.c:2909 [inline]
 __se_sys_bpf+0x2e37/0xbcb0 kernel/bpf/syscall.c:2849
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1
RIP: 0033:0x7f8f7ef4d169
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8f7d5b7038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f8f7f165fa0 RCX: 00007f8f7ef4d169
RDX: 000000000000002c RSI: 0000200000000080 RDI: 000000000000000a
RBP: 00007f8f7efce2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f8f7f165fa0 R15: 00007ffe7f9431d8
Modules linked in:
CR2: 0000000000000000
---[ end trace b4c10fe7fe4b04dc ]---
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffff8881f6f09d78 EFLAGS: 00010002
RAX: ffffffff8154e8ca RBX: 0000000000000102 RCX: ffff8881dee49f80
RDX: 0000000000000102 RSI: 0000000000000000 RDI: ffff8881e1a4f1c0
RBP: ffff8881f6f09f28 R08: ffffffff8154e50e R09: 0000000000000003
R10: ffffffffffffffff R11: dffffc0000000001 R12: 00000000ffff98e8
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881e1a4f1c0
FS:  00007f8f7d5b76c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001dcd08000 CR4: 00000000003406a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400