================================================================== 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 ffff8881ebbcf1c8 by task syz.2.199/1157 CPU: 0 PID: 1157 Comm: syz.2.199 Tainted: G W 5.4.290-syzkaller-00002-g41adfeb3d639 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __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 RIP: 0010:__orc_find arch/x86/kernel/unwind_orc.c:49 [inline] RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:175 [inline] RIP: 0010:unwind_next_frame+0x628/0x1ea0 arch/x86/kernel/unwind_orc.c:438 Code: b9 00 00 00 00 00 fc ff df 0f b6 04 08 84 c0 75 27 48 63 03 48 01 d8 48 8d 4b 04 4c 39 e0 4c 0f 46 e9 48 8d 43 fc 4c 0f 47 f8 <4c> 0f 46 f3 4d 39 fd 76 a8 e9 ec fc ff ff 89 d9 80 e1 07 80 c1 03 RSP: 0018:ffff8881e6116ce0 EFLAGS: 00000297 ORIG_RAX: ffffffffffffff13 RAX: ffffffff864f5dcc RBX: ffffffff864f5dd0 RCX: ffffffff864f5dd4 RDX: ffffffff864f5dc0 RSI: ffffffff86792f20 RDI: ffffffff812fbdbc RBP: ffff8881e6116fd0 R08: 0000000000000009 R09: ffff8881e6117030 R10: 0000000000000000 R11: dffffc0000000001 R12: ffffffff810068f8 R13: ffffffff864f5dd4 R14: ffffffff864f5dc0 R15: ffffffff864f5de0 arch_stack_walk+0x111/0x140 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x118/0x1c0 kernel/stacktrace.c:123 save_stack+0x95/0x880 mm/page_owner.c:122 __reset_page_owner+0x1f/0x100 mm/page_owner.c:149 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_list+0x10a/0x590 mm/page_alloc.c:3154 release_pages+0xad8/0xb20 mm/swap.c:842 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline] tlb_flush_mmu_free mm/mmu_gather.c:189 [inline] tlb_flush_mmu+0xc8/0x170 mm/mmu_gather.c:196 zap_pte_range mm/memory.c:1173 [inline] zap_pmd_range mm/memory.c:1222 [inline] zap_pud_range mm/memory.c:1251 [inline] zap_p4d_range mm/memory.c:1272 [inline] unmap_page_range+0x1d29/0x2620 mm/memory.c:1293 unmap_single_vma mm/memory.c:1338 [inline] unmap_vmas+0x355/0x4b0 mm/memory.c:1370 exit_mmap+0x2bc/0x520 mm/mmap.c:3191 __mmput+0x8e/0x2c0 kernel/fork.c:1101 exit_mm kernel/exit.c:538 [inline] do_exit+0xc08/0x2bc0 kernel/exit.c:848 do_group_exit+0x138/0x300 kernel/exit.c:984 get_signal+0xdb1/0x1440 kernel/signal.c:2738 do_signal+0xb0/0x11f0 arch/x86/kernel/signal.c:809 exit_to_usermode_loop+0xc0/0x1a0 arch/x86/entry/common.c:159 prepare_exit_to_usermode+0x199/0x200 arch/x86/entry/common.c:194 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 RIP: 0033:0x7f305bd89169 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:00007f305a3f3038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: 0000000000000000 RBX: 00007f305bfa1fa0 RCX: 00007f305bd89169 RDX: 00002000000000c0 RSI: 00000000400454ca RDI: 0000000000000004 RBP: 00007f305be0a2a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f305bfa1fa0 R15: 00007ffd28660ca8 The buggy address belongs to the page: page:ffffea0007aef3c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 flags: 0x8000000000000000() raw: 8000000000000000 dead000000000100 dead000000000122 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 2, migratetype Unmovable, gfp_mask 0x146dc0(GFP_USER|__GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_COMP|__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 __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] kmalloc_order mm/slab_common.c:1342 [inline] kmalloc_order_trace+0x2a/0x100 mm/slab_common.c:1358 __kmalloc_node include/linux/slab.h:422 [inline] kmalloc_node include/linux/slab.h:599 [inline] kvmalloc_node+0x7e/0xf0 mm/util.c:596 kvmalloc include/linux/mm.h:761 [inline] kvzalloc include/linux/mm.h:769 [inline] alloc_netdev_mqs+0x85/0xc70 net/core/dev.c:9629 tun_set_iff+0x51f/0xdc0 drivers/net/tun.c:2893 __tun_chr_ioctl+0x8a9/0x1d00 drivers/net/tun.c:3187 do_vfs_ioctl+0x742/0x1720 fs/ioctl.c:47 ksys_ioctl fs/ioctl.c:742 [inline] __do_sys_ioctl fs/ioctl.c:749 [inline] __se_sys_ioctl fs/ioctl.c:747 [inline] __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747 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_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 tun_set_iff+0x870/0xdc0 drivers/net/tun.c:2924 __tun_chr_ioctl+0x8a9/0x1d00 drivers/net/tun.c:3187 do_vfs_ioctl+0x742/0x1720 fs/ioctl.c:47 ksys_ioctl fs/ioctl.c:742 [inline] __do_sys_ioctl fs/ioctl.c:749 [inline] __se_sys_ioctl fs/ioctl.c:747 [inline] __x64_sys_ioctl+0xd4/0x110 fs/ioctl.c:747 do_syscall_64+0xca/0x1c0 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Memory state around the buggy address: ffff8881ebbcf080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8881ebbcf100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff8881ebbcf180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff8881ebbcf200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8881ebbcf280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== ---------------- Code disassembly (best guess): 0: b9 00 00 00 00 mov $0x0,%ecx 5: 00 fc add %bh,%ah 7: ff (bad) 8: df 0f fisttps (%rdi) a: b6 04 mov $0x4,%dh c: 08 84 c0 75 27 48 63 or %al,0x63482775(%rax,%rax,8) 13: 03 48 01 add 0x1(%rax),%ecx 16: d8 48 8d fmuls -0x73(%rax) 19: 4b 04 4c rex.WXB add $0x4c,%al 1c: 39 e0 cmp %esp,%eax 1e: 4c 0f 46 e9 cmovbe %rcx,%r13 22: 48 8d 43 fc lea -0x4(%rbx),%rax 26: 4c 0f 47 f8 cmova %rax,%r15 * 2a: 4c 0f 46 f3 cmovbe %rbx,%r14 <-- trapping instruction 2e: 4d 39 fd cmp %r15,%r13 31: 76 a8 jbe 0xffffffdb 33: e9 ec fc ff ff jmp 0xfffffd24 38: 89 d9 mov %ebx,%ecx 3a: 80 e1 07 and $0x7,%cl 3d: 80 c1 03 add $0x3,%cl