================================================================== BUG: KASAN: use-after-free in __hlist_del include/linux/list.h:791 [inline] BUG: KASAN: use-after-free in detach_timer kernel/time/timer.c:824 [inline] BUG: KASAN: use-after-free in expire_timers kernel/time/timer.c:1482 [inline] BUG: KASAN: use-after-free in __run_timers+0x759/0xb60 kernel/time/timer.c:1817 Write of size 8 at addr ffff8881e4dc71c8 by task syz.4.527/2362 CPU: 1 PID: 2362 Comm: syz.4.527 Not tainted 5.4.292-syzkaller-00021-gcd8e74fa0fa3 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack+0x1e/0x20 lib/dump_stack.c:77 dump_stack+0x15b/0x1b8 lib/dump_stack.c:118 print_address_description+0x8d/0x4c0 mm/kasan/report.c:384 __kasan_report+0xef/0x120 mm/kasan/report.c:516 kasan_report+0x30/0x60 mm/kasan/common.c:653 __asan_report_store8_noabort+0x17/0x20 mm/kasan/generic_report.c:137 __hlist_del include/linux/list.h:791 [inline] detach_timer kernel/time/timer.c:824 [inline] expire_timers kernel/time/timer.c:1482 [inline] __run_timers+0x759/0xb60 kernel/time/timer.c:1817 run_timer_softirq+0x6a/0xf0 kernel/time/timer.c:1830 __do_softirq+0x236/0x660 kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x197/0x1c0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:539 [inline] smp_apic_timer_interrupt+0x11d/0x490 arch/x86/kernel/apic/apic.c:1161 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:834 RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:90 [inline] RIP: 0010:memory_is_nonzero mm/kasan/generic.c:108 [inline] RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:134 [inline] RIP: 0010:memory_is_poisoned mm/kasan/generic.c:165 [inline] RIP: 0010:check_memory_region_inline mm/kasan/generic.c:181 [inline] RIP: 0010:check_memory_region+0x60/0x280 mm/kasan/generic.c:191 Code: c1 eb 03 49 b8 00 00 00 00 00 fc ff df 4f 8d 0c 03 48 8d 5c 37 ff 48 c1 eb 03 4e 8d 14 3b 4d 89 d6 4d 29 ce 49 83 fe 10 7f 26 <4d> 85 f6 0f 84 39 01 00 00 48 f7 d3 4c 01 db 41 80 39 00 0f 85 c2 RSP: 0018:ffff8881e43e7048 EFLAGS: 00000283 ORIG_RAX: ffffffffffffff13 RAX: ffffffff817a1a01 RBX: 1ffffd4000e7efa6 RCX: ffffffff817a1a84 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffea00073f7d34 RBP: ffff8881e43e7060 R08: dffffc0000000000 R09: fffff94000e7efa6 R10: fffff94000e7efa7 R11: 1ffffd4000e7efa6 R12: ffffea00073f7d00 R13: dffffc0000000000 R14: 0000000000000001 R15: dffffc0000000001 __kasan_check_read+0x11/0x20 mm/kasan/common.c:93 atomic_read include/asm-generic/atomic-instrumented.h:26 [inline] atomic_fetch_add_unless include/linux/atomic-fallback.h:1086 [inline] atomic_add_unless include/linux/atomic-fallback.h:1111 [inline] page_ref_add_unless include/linux/page_ref.h:157 [inline] __page_cache_add_speculative include/linux/pagemap.h:189 [inline] page_cache_get_speculative include/linux/pagemap.h:205 [inline] filemap_map_pages+0x264/0xb00 mm/filemap.c:2783 do_fault_around mm/memory.c:3658 [inline] do_read_fault mm/memory.c:3693 [inline] do_fault mm/memory.c:3828 [inline] handle_pte_fault mm/memory.c:4059 [inline] __handle_mm_fault mm/memory.c:4183 [inline] handle_mm_fault+0x1ede/0x3930 mm/memory.c:4220 faultin_page mm/gup.c:654 [inline] __get_user_pages+0xc50/0x15d0 mm/gup.c:874 get_dump_page+0xd1/0x140 mm/gup.c:1363 elf_core_dump+0x3438/0x3bd0 fs/binfmt_elf.c:2349 do_coredump+0x1d8c/0x2ab0 fs/coredump.c:801 get_signal+0xdb7/0x13d0 kernel/signal.c:2732 do_signal+0xad/0xda0 arch/x86/kernel/signal.c:809 exit_to_usermode_loop+0xc4/0x1b0 arch/x86/entry/common.c:159 prepare_exit_to_usermode+0x18e/0x1f0 arch/x86/entry/common.c:194 ret_from_intr+0x1c/0x1c RIP: 0033:0x9ea3 Code: Bad RIP value. RSP: 002b:0000200000000278 EFLAGS: 00010217 RAX: 0000000000000000 RBX: 00007fb80b6a7080 RCX: 00007fb80b47f969 RDX: 0000200000000280 RSI: 0000200000000270 RDI: 0000000000108000 RBP: 00007fb80b501ab1 R08: 0000200000000300 R09: 0000200000000300 R10: 00002000000002c0 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fb80b6a7080 R15: 00007fff1b6604d8 Allocated by task 2367: save_stack mm/kasan/common.c:70 [inline] set_track mm/kasan/common.c:78 [inline] __kasan_kmalloc+0x162/0x200 mm/kasan/common.c:529 kasan_slab_alloc+0x12/0x20 mm/kasan/common.c:537 slab_post_alloc_hook mm/slab.h:584 [inline] slab_alloc_node mm/slub.c:2829 [inline] slab_alloc mm/slub.c:2837 [inline] __kmalloc_track_caller+0x10d/0x2d0 mm/slub.c:4449 __kmalloc_reserve net/core/skbuff.c:142 [inline] pskb_expand_head+0x123/0x1110 net/core/skbuff.c:1653 skb_ensure_writable+0x2e7/0x460 net/core/skbuff.c:5569 __bpf_try_make_writable net/core/filter.c:1635 [inline] bpf_try_make_writable net/core/filter.c:1641 [inline] bpf_try_make_head_writable net/core/filter.c:1649 [inline] ____bpf_clone_redirect net/core/filter.c:2145 [inline] bpf_clone_redirect+0x10b/0x380 net/core/filter.c:2123 bpf_prog_ea5dd1b4147210ac+0x9e7/0x1000 bpf_call_func include/linux/filter.h:627 [inline] bpf_test_run+0x1ea/0x5d0 net/bpf/test_run.c:44 bpf_prog_test_run_skb+0x721/0xdc0 net/bpf/test_run.c:311 bpf_prog_test_run+0x21a/0x2a0 kernel/bpf/syscall.c:2124 __do_sys_bpf kernel/bpf/syscall.c:2909 [inline] __se_sys_bpf+0x49a/0x570 kernel/bpf/syscall.c:2849 __x64_sys_bpf+0x7b/0x90 kernel/bpf/syscall.c:2849 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Freed by task 2367: 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+0x1c3/0x280 mm/kasan/common.c:487 kasan_slab_free+0xe/0x10 mm/kasan/common.c:496 slab_free_hook mm/slub.c:1455 [inline] slab_free_freelist_hook+0xb7/0x180 mm/slub.c:1494 slab_free mm/slub.c:3080 [inline] kfree+0xbe/0x260 mm/slub.c:4071 skb_free_head net/core/skbuff.c:601 [inline] skb_release_data+0x4ea/0x610 net/core/skbuff.c:621 skb_release_all net/core/skbuff.c:675 [inline] __kfree_skb net/core/skbuff.c:689 [inline] kfree_skb+0xbc/0x3a0 net/core/skbuff.c:708 tun_net_xmit+0x947/0xfa0 drivers/net/tun.c:1199 __netdev_start_xmit include/linux/netdevice.h:4544 [inline] netdev_start_xmit include/linux/netdevice.h:4558 [inline] xmit_one net/core/dev.c:3221 [inline] dev_hard_start_xmit+0x1ef/0x6f0 net/core/dev.c:3237 sch_direct_xmit+0x24b/0x8b0 net/sched/sch_generic.c:336 qdisc_restart net/sched/sch_generic.c:401 [inline] __qdisc_run+0x954/0x1370 net/sched/sch_generic.c:409 qdisc_run+0x10a/0x300 include/net/pkt_sched.h:122 __dev_xmit_skb net/core/dev.c:3432 [inline] __dev_queue_xmit+0x9dd/0x2400 net/core/dev.c:3787 dev_queue_xmit+0x17/0x20 net/core/dev.c:3854 __bpf_tx_skb net/core/filter.c:2063 [inline] __bpf_redirect_common net/core/filter.c:2111 [inline] __bpf_redirect+0x9f9/0xe30 net/core/filter.c:2118 ____bpf_clone_redirect net/core/filter.c:2151 [inline] bpf_clone_redirect+0x242/0x380 net/core/filter.c:2123 bpf_prog_ea5dd1b4147210ac+0x9e7/0x1000 bpf_call_func include/linux/filter.h:627 [inline] bpf_test_run+0x1ea/0x5d0 net/bpf/test_run.c:44 bpf_prog_test_run_skb+0x721/0xdc0 net/bpf/test_run.c:311 bpf_prog_test_run+0x21a/0x2a0 kernel/bpf/syscall.c:2124 __do_sys_bpf kernel/bpf/syscall.c:2909 [inline] __se_sys_bpf+0x49a/0x570 kernel/bpf/syscall.c:2849 __x64_sys_bpf+0x7b/0x90 kernel/bpf/syscall.c:2849 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 The buggy address belongs to the object at ffff8881e4dc7000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 456 bytes inside of 512-byte region [ffff8881e4dc7000, ffff8881e4dc7200) The buggy address belongs to the page: page:ffffea0007937100 refcount:1 mapcount:0 mapping:ffff8881f5c02500 index:0x0 compound_mapcount: 0 flags: 0x8000000000010200(slab|head) raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5c02500 raw: 0000000000000000 0000000000100010 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 0x1d2a20(GFP_ATOMIC|__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+0x35e/0x370 mm/page_alloc.c:2171 get_page_from_freelist+0x1296/0x1310 mm/page_alloc.c:3794 __alloc_pages_nodemask+0x202/0x4b0 mm/page_alloc.c:4894 alloc_slab_page+0x3c/0x3b0 mm/slub.c:343 allocate_slab mm/slub.c:1683 [inline] new_slab+0x93/0x420 mm/slub.c:1749 new_slab_objects mm/slub.c:2505 [inline] ___slab_alloc+0x29e/0x420 mm/slub.c:2667 __slab_alloc+0x63/0xa0 mm/slub.c:2707 slab_alloc_node mm/slub.c:2792 [inline] slab_alloc mm/slub.c:2837 [inline] __kmalloc_track_caller+0x17c/0x2d0 mm/slub.c:4449 __kmalloc_reserve net/core/skbuff.c:142 [inline] pskb_expand_head+0x123/0x1110 net/core/skbuff.c:1653 skb_ensure_writable+0x2e7/0x460 net/core/skbuff.c:5569 __bpf_try_make_writable net/core/filter.c:1635 [inline] bpf_try_make_writable net/core/filter.c:1641 [inline] bpf_try_make_head_writable net/core/filter.c:1649 [inline] ____bpf_clone_redirect net/core/filter.c:2145 [inline] bpf_clone_redirect+0x10b/0x380 net/core/filter.c:2123 bpf_prog_ea5dd1b4147210ac+0x9e7/0x1000 bpf_call_func include/linux/filter.h:627 [inline] bpf_test_run+0x1ea/0x5d0 net/bpf/test_run.c:44 bpf_prog_test_run_skb+0x721/0xdc0 net/bpf/test_run.c:311 bpf_prog_test_run+0x21a/0x2a0 kernel/bpf/syscall.c:2124 __do_sys_bpf kernel/bpf/syscall.c:2909 [inline] __se_sys_bpf+0x49a/0x570 kernel/bpf/syscall.c:2849 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+0x7e4/0x910 mm/page_alloc.c:1438 free_the_page mm/page_alloc.c:4956 [inline] __free_pages+0x8c/0x110 mm/page_alloc.c:4962 kfree+0x1ca/0x260 mm/slub.c:4068 kvfree+0x4c/0x50 mm/util.c:625 netdev_freemem+0x3f/0x60 net/core/dev.c:9583 netdev_release+0x7f/0xb0 net/core/net-sysfs.c:1743 device_release+0x70/0x1a0 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+0x1fe/0x2c0 lib/kobject.c:764 netdev_run_todo+0xae4/0xc70 net/core/dev.c:9488 rtnl_unlock+0xe/0x10 net/core/rtnetlink.c:112 tun_detach drivers/net/tun.c:766 [inline] tun_chr_close+0xc4/0x140 drivers/net/tun.c:3563 __fput+0x2a3/0x730 fs/file_table.c:281 ____fput+0x15/0x20 fs/file_table.c:314 task_work_run+0x146/0x170 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0xa43/0x2660 kernel/exit.c:861 __do_sys_exit kernel/exit.c:953 [inline] __se_sys_exit kernel/exit.c:951 [inline] __ia32_sys_exit+0x0/0x40 kernel/exit.c:951 Memory state around the buggy address: ffff8881e4dc7080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881e4dc7100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881e4dc7180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881e4dc7200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8881e4dc7280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page PGD 1c9b08067 P4D 1c9b08067 PUD 0 Oops: 0010 [#1] PREEMPT SMP KASAN CPU: 1 PID: 2362 Comm: syz.4.527 Tainted: G B 5.4.292-syzkaller-00021-gcd8e74fa0fa3 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 RIP: 0010:0x0 Code: Bad RIP value. RSP: 0018:ffff8881f6f09cf0 EFLAGS: 00010202 RAX: ffffffff8150a590 RBX: 0000000000000101 RCX: ffff8881e88cee40 RDX: 0000000000000101 RSI: 0000000000000000 RDI: ffff8881e4dc71c0 RBP: ffff8881f6f09d30 R08: 0000000000000004 R09: 0000000000000003 R10: ffffed103ede1398 R11: 1ffff1103ede1398 R12: 0000000100002718 R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881e4dc71c0 FS: 00007fb809ac76c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 00000001eb1de000 CR4: 00000000003406a0 DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: call_timer_fn+0x3c/0x380 kernel/time/timer.c:1448 expire_timers kernel/time/timer.c:1493 [inline] __run_timers+0x81d/0xb60 kernel/time/timer.c:1817 run_timer_softirq+0x6a/0xf0 kernel/time/timer.c:1830 __do_softirq+0x236/0x660 kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x197/0x1c0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:539 [inline] smp_apic_timer_interrupt+0x11d/0x490 arch/x86/kernel/apic/apic.c:1161 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:834 RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:90 [inline] RIP: 0010:memory_is_nonzero mm/kasan/generic.c:108 [inline] RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:134 [inline] RIP: 0010:memory_is_poisoned mm/kasan/generic.c:165 [inline] RIP: 0010:check_memory_region_inline mm/kasan/generic.c:181 [inline] RIP: 0010:check_memory_region+0x60/0x280 mm/kasan/generic.c:191 Code: c1 eb 03 49 b8 00 00 00 00 00 fc ff df 4f 8d 0c 03 48 8d 5c 37 ff 48 c1 eb 03 4e 8d 14 3b 4d 89 d6 4d 29 ce 49 83 fe 10 7f 26 <4d> 85 f6 0f 84 39 01 00 00 48 f7 d3 4c 01 db 41 80 39 00 0f 85 c2 RSP: 0018:ffff8881e43e7048 EFLAGS: 00000283 ORIG_RAX: ffffffffffffff13 RAX: ffffffff817a1a01 RBX: 1ffffd4000e7efa6 RCX: ffffffff817a1a84 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffea00073f7d34 RBP: ffff8881e43e7060 R08: dffffc0000000000 R09: fffff94000e7efa6 R10: fffff94000e7efa7 R11: 1ffffd4000e7efa6 R12: ffffea00073f7d00 R13: dffffc0000000000 R14: 0000000000000001 R15: dffffc0000000001 __kasan_check_read+0x11/0x20 mm/kasan/common.c:93 atomic_read include/asm-generic/atomic-instrumented.h:26 [inline] atomic_fetch_add_unless include/linux/atomic-fallback.h:1086 [inline] atomic_add_unless include/linux/atomic-fallback.h:1111 [inline] page_ref_add_unless include/linux/page_ref.h:157 [inline] __page_cache_add_speculative include/linux/pagemap.h:189 [inline] page_cache_get_speculative include/linux/pagemap.h:205 [inline] filemap_map_pages+0x264/0xb00 mm/filemap.c:2783 do_fault_around mm/memory.c:3658 [inline] do_read_fault mm/memory.c:3693 [inline] do_fault mm/memory.c:3828 [inline] handle_pte_fault mm/memory.c:4059 [inline] __handle_mm_fault mm/memory.c:4183 [inline] handle_mm_fault+0x1ede/0x3930 mm/memory.c:4220 faultin_page mm/gup.c:654 [inline] __get_user_pages+0xc50/0x15d0 mm/gup.c:874 get_dump_page+0xd1/0x140 mm/gup.c:1363 elf_core_dump+0x3438/0x3bd0 fs/binfmt_elf.c:2349 do_coredump+0x1d8c/0x2ab0 fs/coredump.c:801 get_signal+0xdb7/0x13d0 kernel/signal.c:2732 do_signal+0xad/0xda0 arch/x86/kernel/signal.c:809 exit_to_usermode_loop+0xc4/0x1b0 arch/x86/entry/common.c:159 prepare_exit_to_usermode+0x18e/0x1f0 arch/x86/entry/common.c:194 ret_from_intr+0x1c/0x1c RIP: 0033:0x9ea3 Code: Bad RIP value. RSP: 002b:0000200000000278 EFLAGS: 00010217 RAX: 0000000000000000 RBX: 00007fb80b6a7080 RCX: 00007fb80b47f969 RDX: 0000200000000280 RSI: 0000200000000270 RDI: 0000000000108000 RBP: 00007fb80b501ab1 R08: 0000200000000300 R09: 0000200000000300 R10: 00002000000002c0 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fb80b6a7080 R15: 00007fff1b6604d8 Modules linked in: CR2: 0000000000000000 ---[ end trace 4bca74aee38d1e27 ]--- RIP: 0010:0x0 Code: Bad RIP value. RSP: 0018:ffff8881f6f09cf0 EFLAGS: 00010202 RAX: ffffffff8150a590 RBX: 0000000000000101 RCX: ffff8881e88cee40 RDX: 0000000000000101 RSI: 0000000000000000 RDI: ffff8881e4dc71c0 RBP: ffff8881f6f09d30 R08: 0000000000000004 R09: 0000000000000003 R10: ffffed103ede1398 R11: 1ffff1103ede1398 R12: 0000000100002718 R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881e4dc71c0 FS: 00007fb809ac76c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 00000001eb1de000 CR4: 00000000003406a0 DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 ---------------- Code disassembly (best guess): 0: c1 eb 03 shr $0x3,%ebx 3: 49 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%r8 a: fc ff df d: 4f 8d 0c 03 lea (%r11,%r8,1),%r9 11: 48 8d 5c 37 ff lea -0x1(%rdi,%rsi,1),%rbx 16: 48 c1 eb 03 shr $0x3,%rbx 1a: 4e 8d 14 3b lea (%rbx,%r15,1),%r10 1e: 4d 89 d6 mov %r10,%r14 21: 4d 29 ce sub %r9,%r14 24: 49 83 fe 10 cmp $0x10,%r14 28: 7f 26 jg 0x50 * 2a: 4d 85 f6 test %r14,%r14 <-- trapping instruction 2d: 0f 84 39 01 00 00 je 0x16c 33: 48 f7 d3 not %rbx 36: 4c 01 db add %r11,%rbx 39: 41 80 39 00 cmpb $0x0,(%r9) 3d: 0f .byte 0xf 3e: 85 c2 test %eax,%edx