==================================================================
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 ffff8881f04071c8 by task syz.4.1795/5754

CPU: 1 PID: 5754 Comm: syz.4.1795 Not tainted 5.4.274-syzkaller-00002-g6f97bd951d82 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
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
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x195/0x1c0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:538 [inline]
 smp_apic_timer_interrupt+0x11a/0x460 arch/x86/kernel/apic/apic.c:1149
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:834
 </IRQ>
RIP: 0033:0x7fd683e6927a
Code: 01 00 00 00 31 c0 41 89 f8 44 89 f1 4d 8b 65 28 49 8d 0c cf 4e 03 24 09 80 3d 67 ae 2a 00 00 0f 85 93 01 00 00 bf 00 00 00 80 <49> 8d 0c 3c 48 81 f9 ff ff ff 7e 76 19 4c 89 e6 48 8d 3d a9 14 1a
RSP: 002b:00007ffe0976e280 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffffffff837e7bb2 RBX: 00007fd684c49720 RCX: 00007fd6838f8330
RDX: 0000000000000001 RSI: 0000000000001428 RDI: 0000000080000000
RBP: ffffffff837e7427 R08: 000000000000056d R09: 0000000000000008
R10: 00000000837e7427 R11: 00000000837e742b R12: ffffffff837e7df2
R13: 00007fd684118038 R14: 000000000001ca66 R15: 00007fd683813000

The buggy address belongs to the page:
page:ffffea0007c101c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x8000000000000000()
raw: 8000000000000000 ffffea0007708f08 ffffea0007c10188 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x102dc2(GFP_HIGHUSER|__GFP_NOWARN|__GFP_ZERO)
 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
 __vmalloc_area_node mm/vmalloc.c:2431 [inline]
 __vmalloc_node_range+0x384/0x710 mm/vmalloc.c:2499
 vmalloc_user+0x70/0x80 mm/vmalloc.c:2629
 kcov_mmap+0x28/0x120 kernel/kcov.c:450
 call_mmap include/linux/fs.h:1994 [inline]
 mmap_region+0x110d/0x16f0 mm/mmap.c:1812
 do_mmap+0x822/0xd30 mm/mmap.c:1581
 do_mmap_pgoff include/linux/mm.h:2480 [inline]
 vm_mmap_pgoff+0x1b5/0x260 mm/util.c:528
 ksys_mmap_pgoff+0x168/0x1e0 mm/mmap.c:1631
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1
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_pcp_prepare mm/page_alloc.c:1233 [inline]
 free_unref_page_prepare+0x297/0x380 mm/page_alloc.c:3085
 free_unref_page mm/page_alloc.c:3134 [inline]
 free_the_page mm/page_alloc.c:4953 [inline]
 __free_pages+0xaf/0x140 mm/page_alloc.c:4961
 __vunmap+0x75b/0x890 mm/vmalloc.c:2260
 kcov_put kernel/kcov.c:396 [inline]
 kcov_close+0x27/0x50 kernel/kcov.c:495
 __fput+0x262/0x680 fs/file_table.c:281
 task_work_run+0x140/0x170 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0xcaf/0x2bc0 kernel/exit.c:859
 do_group_exit+0x138/0x300 kernel/exit.c:982
 __do_sys_exit_group kernel/exit.c:993 [inline]
 __se_sys_exit_group kernel/exit.c:991 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:991
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1

Memory state around the buggy address:
 ffff8881f0407080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881f0407100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8881f0407180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff8881f0407200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881f0407280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================