==================================================================
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 ffff8881cbbab1c8 by task syz.3.857/3797

CPU: 1 PID: 3797 Comm: syz.3.857 Not tainted 5.4.290-syzkaller-00017-g6b07fcd94a6a #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
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x195/0x1c0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:539 [inline]
 smp_apic_timer_interrupt+0x11a/0x490 arch/x86/kernel/apic/apic.c:1161
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:834
 </IRQ>
RIP: 0010:preempt_count_sub+0x2/0x160 kernel/sched/core.c:4035
Code: c7 c1 c4 79 4c 86 80 e1 07 80 c1 03 38 c1 7c 80 48 c7 c7 c4 79 4c 86 e8 5c 43 4f 00 e9 6f ff ff ff 0f 1f 80 00 00 00 00 41 56 <53> 89 fb 48 c7 c0 c0 49 eb 86 48 c1 e8 03 49 be 00 00 00 00 00 fc
RSP: 0018:ffff8881e5e3f1b0 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff13
RAX: ffff8881e5e40000 RBX: ffff8881e5e3f4d0 RCX: ffff8881e5e3fa20
RDX: ffff8881e5e3f500 RSI: ffff8881e5e3f140 RDI: 0000000000000001
RBP: ffff8881e5e3f4b0 R08: dffffc0000000000 R09: ffff8881e5e3f510
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffffffff0d505b6
R13: ffffffff86a82db5 R14: ffff8881e5e3fa18 R15: ffff8881e5e38000
 unwind_next_frame+0x176a/0x1ea0 arch/x86/kernel/unwind_orc.c:603
 arch_stack_walk+0x111/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x118/0x1c0 kernel/stacktrace.c:123
 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
 kmalloc include/linux/slab.h:556 [inline]
 ipv4_inetpeer_init+0x4b/0xa0 net/ipv4/route.c:3450
 ops_init+0x1d4/0x4a0 net/core/net_namespace.c:141
 setup_net+0x214/0x990 net/core/net_namespace.c:348
 copy_net_ns+0x30d/0x510 net/core/net_namespace.c:489
 create_new_namespaces+0x47a/0x570 kernel/nsproxy.c:103
 copy_namespaces+0x169/0x1b0 kernel/nsproxy.c:161
 copy_process+0x12da/0x3230 kernel/fork.c:2055
 _do_fork+0x197/0x900 kernel/fork.c:2399
 __do_sys_clone kernel/fork.c:2557 [inline]
 __se_sys_clone kernel/fork.c:2538 [inline]
 __x64_sys_clone+0x26b/0x2c0 kernel/fork.c:2538
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1
RIP: 0033:0x7f6d80e95169
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:00007f6d7f4fefe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f6d810adfa0 RCX: 00007f6d80e95169
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000c3002000
RBP: 00007f6d80f162a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f6d810adfa0 R15: 00007fff19ef5468

The buggy address belongs to the page:
page:ffffea00072eeac0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x8000000000000000()
raw: 8000000000000000 ffff8881e28c7ac0 ffffea00072eea88 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 0x102cc2(GFP_HIGHUSER|__GFP_NOWARN)
 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_pages include/linux/gfp.h:503 [inline]
 __alloc_pages_node include/linux/gfp.h:516 [inline]
 alloc_pages_node include/linux/gfp.h:530 [inline]
 pcpu_alloc_pages mm/percpu-vm.c:94 [inline]
 pcpu_populate_chunk+0x1bb/0xd00 mm/percpu-vm.c:284
 pcpu_alloc+0x79e/0x1050 mm/percpu.c:1714
 prealloc_init+0x238/0x800 kernel/bpf/hashtab.c:154
 htab_map_alloc+0x638/0x930 kernel/bpf/hashtab.c:385
 find_and_alloc_map kernel/bpf/syscall.c:122 [inline]
 map_create kernel/bpf/syscall.c:573 [inline]
 __do_sys_bpf kernel/bpf/syscall.c:2873 [inline]
 __se_sys_bpf+0x3291/0xbcb0 kernel/bpf/syscall.c:2849
 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
 pcpu_free_pages mm/percpu-vm.c:64 [inline]
 pcpu_depopulate_chunk mm/percpu-vm.c:328 [inline]
 pcpu_balance_workfn+0x940/0x1450 mm/percpu.c:1865
 process_one_work+0x765/0xd20 kernel/workqueue.c:2290
 worker_thread+0xaef/0x1470 kernel/workqueue.c:2436
 kthread+0x2da/0x360 kernel/kthread.c:288
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:354

Memory state around the buggy address:
 ffff8881cbbab080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881cbbab100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8881cbbab180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff8881cbbab200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881cbbab280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 1e6b52067 P4D 1e6b52067 PUD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 3797 Comm: syz.3.857 Tainted: G    B             5.4.290-syzkaller-00017-g6b07fcd94a6a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffff8881f6f09d18 EFLAGS: 00010206
RAX: ffffffff8154e8ca RBX: 0000000000000100 RCX: ffff8881dfa20fc0
RDX: 0000000080000100 RSI: 0000000000000000 RDI: ffff8881cbbab1c0
RBP: ffff8881f6f09ec8 R08: ffffffff8154e50e R09: 0000000000000003
R10: ffffffffffffffff R11: dffffc0000000001 R12: 00000000ffffd830
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881cbbab1c0
FS:  00007f6d7f4ff6c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001e3068000 CR4: 00000000003406a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 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:539 [inline]
 smp_apic_timer_interrupt+0x11a/0x490 arch/x86/kernel/apic/apic.c:1161
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:834
 </IRQ>
RIP: 0010:unwind_next_frame+0x106/0x1ea0 arch/x86/kernel/unwind_orc.c:414
Code: 00 00 00 00 00 00 4d 8d 66 48 4c 89 e0 48 c1 e8 03 48 89 44 24 30 42 80 3c 38 00 74 08 4c 89 e7 e8 ef 77 64 00 4c 89 64 24 20 <4d> 8b 6e 48 4d 8d 66 38 4c 89 e0 48 c1 e8 03 48 89 44 24 60 42 80
RSP: 0018:ffff8881e5e3f160 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffff1103cbc7e95 RBX: 1ffff1103cbc7e40 RCX: 0000000000000002
RDX: ffffc900005af000 RSI: 0000000000000040 RDI: ffff8881e5e3f3e0
RBP: ffff8881e5e3f450 R08: ffffffff8153c592 R09: ffff8881e5e3f4b0
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff8881e5e3f4a8
R13: ffffffff8153c430 R14: ffff8881e5e3f460 R15: dffffc0000000000
 arch_stack_walk+0x111/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x118/0x1c0 kernel/stacktrace.c:123
 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
 kmalloc include/linux/slab.h:556 [inline]
 kzalloc include/linux/slab.h:690 [inline]
 fib6_net_init+0x143/0x830 net/ipv6/ip6_fib.c:2262
 ops_init+0x1d4/0x4a0 net/core/net_namespace.c:141
 setup_net+0x214/0x990 net/core/net_namespace.c:348
 copy_net_ns+0x30d/0x510 net/core/net_namespace.c:489
 create_new_namespaces+0x47a/0x570 kernel/nsproxy.c:103
 copy_namespaces+0x169/0x1b0 kernel/nsproxy.c:161
 copy_process+0x12da/0x3230 kernel/fork.c:2055
 _do_fork+0x197/0x900 kernel/fork.c:2399
 __do_sys_clone kernel/fork.c:2557 [inline]
 __se_sys_clone kernel/fork.c:2538 [inline]
 __x64_sys_clone+0x26b/0x2c0 kernel/fork.c:2538
 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1
RIP: 0033:0x7f6d80e95169
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:00007f6d7f4fefe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f6d810adfa0 RCX: 00007f6d80e95169
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000c3002000
RBP: 00007f6d80f162a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f6d810adfa0 R15: 00007fff19ef5468
Modules linked in:
CR2: 0000000000000000
---[ end trace ef10dc5849a85060 ]---
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffff8881f6f09d18 EFLAGS: 00010206
RAX: ffffffff8154e8ca RBX: 0000000000000100 RCX: ffff8881dfa20fc0
RDX: 0000000080000100 RSI: 0000000000000000 RDI: ffff8881cbbab1c0
RBP: ffff8881f6f09ec8 R08: ffffffff8154e50e R09: 0000000000000003
R10: ffffffffffffffff R11: dffffc0000000001 R12: 00000000ffffd830
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881cbbab1c0
FS:  00007f6d7f4ff6c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001e3068000 CR4: 00000000003406a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
----------------
Code disassembly (best guess):
   0:	c7 c1 c4 79 4c 86    	mov    $0x864c79c4,%ecx
   6:	80 e1 07             	and    $0x7,%cl
   9:	80 c1 03             	add    $0x3,%cl
   c:	38 c1                	cmp    %al,%cl
   e:	7c 80                	jl     0xffffff90
  10:	48 c7 c7 c4 79 4c 86 	mov    $0xffffffff864c79c4,%rdi
  17:	e8 5c 43 4f 00       	call   0x4f4378
  1c:	e9 6f ff ff ff       	jmp    0xffffff90
  21:	0f 1f 80 00 00 00 00 	nopl   0x0(%rax)
  28:	41 56                	push   %r14
* 2a:	53                   	push   %rbx <-- trapping instruction
  2b:	89 fb                	mov    %edi,%ebx
  2d:	48 c7 c0 c0 49 eb 86 	mov    $0xffffffff86eb49c0,%rax
  34:	48 c1 e8 03          	shr    $0x3,%rax
  38:	49                   	rex.WB
  39:	be 00 00 00 00       	mov    $0x0,%esi
  3e:	00 fc                	add    %bh,%ah