================================================================== BUG: KASAN: use-after-free in tw_timer_handler+0x8f/0xf0 include/net/net_namespace.h:-1 Read of size 8 at addr ffff88810bb6ce90 by task kworker/u4:0/7 CPU: 0 PID: 7 Comm: kworker/u4:0 Tainted: G W 5.10.238-syzkaller-00282-gd76d4cd0623a #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: netns cleanup_net Call Trace: __dump_stack+0x21/0x24 lib/dump_stack.c:77 dump_stack_lvl+0x169/0x1d8 lib/dump_stack.c:118 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:435 [inline] kasan_report+0xe2/0x130 mm/kasan/report.c:452 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309 tw_timer_handler+0x8f/0xf0 include/net/net_namespace.h:-1 call_timer_fn+0x38/0x290 kernel/time/timer.c:1450 expire_timers kernel/time/timer.c:1495 [inline] __run_timers+0x639/0x9a0 kernel/time/timer.c:1789 run_timer_softirq+0x6a/0xf0 kernel/time/timer.c:1802 __do_softirq+0x255/0x563 kernel/softirq.c:309 asm_call_irq_on_stack+0xf/0x20 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline] run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline] do_softirq_own_stack+0x60/0x80 arch/x86/kernel/irq_64.c:77 invoke_softirq kernel/softirq.c:405 [inline] __irq_exit_rcu+0x128/0x150 kernel/softirq.c:435 irq_exit_rcu+0x9/0x10 kernel/softirq.c:447 sysvec_apic_timer_interrupt+0xbf/0xe0 arch/x86/kernel/apic/apic.c:1106 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:635 RIP: 0010:unwind_next_frame+0x3a2/0x700 arch/x86/kernel/unwind_frame.c:301 Code: 75 d0 4c 8b 6d c0 74 08 4c 89 e7 e8 98 de 6e 00 49 8b 04 24 eb 38 65 48 8b 05 9a c7 d3 7e 48 39 45 a8 4c 8b 75 d0 4c 8b 6d c0 <74> 0a 4c 89 ff e8 54 03 00 00 eb 18 4c 89 f8 48 c1 e8 03 80 3c 10 RSP: 0018:ffffc90000077388 EFLAGS: 00000246 RAX: ffff8881002493c0 RBX: ffffc90000077408 RCX: 1ffff9200000ee01 RDX: dffffc0000000000 RSI: ffffffff81539938 RDI: ffffc90000077f48 RBP: ffffc900000773f8 R08: ffffc900000774d0 R09: ffffc900000774c8 R10: 0000000000000000 R11: 1ffff9200000ee81 R12: 0000000000000000 R13: 1ffff9200000ee8c R14: ffffc90000077460 R15: ffffc90000077490 arch_stack_walk+0x108/0x140 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x98/0xe0 kernel/stacktrace.c:121 kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:430 [inline] ____kasan_kmalloc mm/kasan/common.c:509 [inline] __kasan_kmalloc+0xda/0x110 mm/kasan/common.c:518 kasan_kmalloc include/linux/kasan.h:254 [inline] __kmalloc+0x1a7/0x330 mm/slub.c:4033 kmalloc include/linux/slab.h:557 [inline] kzalloc include/linux/slab.h:664 [inline] kobject_get_path+0xbf/0x1f0 lib/kobject.c:184 kobject_uevent_env+0x28b/0x700 lib/kobject_uevent.c:544 kobject_uevent+0x1d/0x30 lib/kobject_uevent.c:657 __kobject_del+0xd7/0x2f0 lib/kobject.c:625 kobject_cleanup lib/kobject.c:704 [inline] kobject_release lib/kobject.c:744 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1db/0x270 lib/kobject.c:761 netdev_queue_update_kobjects+0x326/0x390 net/core/net-sysfs.c:1709 remove_queue_kobjects net/core/net-sysfs.c:1806 [inline] netdev_unregister_kobject+0x110/0x250 net/core/net-sysfs.c:1959 unregister_netdevice_many+0x1459/0x1980 net/core/dev.c:10794 sit_exit_batch_net+0x607/0x650 net/ipv6/sit.c:1943 ops_exit_list net/core/net_namespace.c:190 [inline] cleanup_net+0x5fb/0xb70 net/core/net_namespace.c:609 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301 worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447 kthread+0x346/0x3d0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 Allocated by task 8809: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:430 [inline] __kasan_slab_alloc+0xbd/0xf0 mm/kasan/common.c:463 kasan_slab_alloc include/linux/kasan.h:244 [inline] slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:583 slab_alloc_node mm/slub.c:2947 [inline] slab_alloc mm/slub.c:2955 [inline] kmem_cache_alloc+0x165/0x2e0 mm/slub.c:2960 kmem_cache_zalloc include/linux/slab.h:654 [inline] net_alloc net/core/net_namespace.c:421 [inline] copy_net_ns+0x13f/0x520 net/core/net_namespace.c:473 create_new_namespaces+0x3a2/0x650 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0x120/0x170 kernel/nsproxy.c:231 ksys_unshare+0x4ac/0x7d0 kernel/fork.c:3156 __do_sys_unshare kernel/fork.c:3224 [inline] __se_sys_unshare kernel/fork.c:3222 [inline] __x64_sys_unshare+0x38/0x40 kernel/fork.c:3222 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb Freed by task 7: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track+0x4a/0x70 mm/kasan/common.c:45 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370 kasan_slab_free include/linux/kasan.h:220 [inline] slab_free_hook mm/slub.c:1595 [inline] slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1621 slab_free mm/slub.c:3203 [inline] kmem_cache_free+0x100/0x2d0 mm/slub.c:3219 net_free net/core/net_namespace.c:449 [inline] net_drop_ns net/core/net_namespace.c:456 [inline] cleanup_net+0xae3/0xb70 net/core/net_namespace.c:630 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301 worker_thread+0xa6a/0x13b0 kernel/workqueue.c:2447 kthread+0x346/0x3d0 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 The buggy address belongs to the object at ffff88810bb6cd00 which belongs to the cache net_namespace of size 4672 The buggy address is located 400 bytes inside of 4672-byte region [ffff88810bb6cd00, ffff88810bb6df40) The buggy address belongs to the page: page:ffffea00042eda00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88810bb6b9c0 pfn:0x10bb68 head:ffffea00042eda00 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head) raw: 4000000000010200 0000000000000000 0000000100000001 ffff888107fdc600 raw: ffff88810bb6b9c0 0000000080060004 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 2252, ts 119126822481, free_ts 119066028571 set_page_owner include/linux/page_owner.h:35 [inline] post_alloc_hook mm/page_alloc.c:2456 [inline] prep_new_page+0x179/0x180 mm/page_alloc.c:2462 get_page_from_freelist+0x2235/0x23d0 mm/page_alloc.c:4254 __alloc_pages_nodemask+0x268/0x5f0 mm/page_alloc.c:5357 alloc_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1808 [inline] new_slab+0x84/0x3f0 mm/slub.c:1869 new_slab_objects mm/slub.c:2627 [inline] ___slab_alloc+0x2a6/0x450 mm/slub.c:2791 __slab_alloc+0x63/0xa0 mm/slub.c:2831 slab_alloc_node mm/slub.c:2913 [inline] slab_alloc mm/slub.c:2955 [inline] kmem_cache_alloc+0x1af/0x2e0 mm/slub.c:2960 kmem_cache_zalloc include/linux/slab.h:654 [inline] net_alloc net/core/net_namespace.c:421 [inline] copy_net_ns+0x13f/0x520 net/core/net_namespace.c:473 create_new_namespaces+0x3a2/0x650 kernel/nsproxy.c:110 copy_namespaces+0x1d1/0x220 kernel/nsproxy.c:179 copy_process+0x11b8/0x32c0 kernel/fork.c:2271 kernel_clone+0x23f/0x940 kernel/fork.c:2650 __do_sys_clone3 kernel/fork.c:2934 [inline] __se_sys_clone3 kernel/fork.c:2918 [inline] __x64_sys_clone3+0x296/0x2f0 kernel/fork.c:2918 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb page last free stack trace: reset_page_owner include/linux/page_owner.h:28 [inline] free_pages_prepare mm/page_alloc.c:1349 [inline] __free_pages_ok+0x7fc/0x820 mm/page_alloc.c:1629 free_the_page mm/page_alloc.c:5418 [inline] __free_pages+0xdd/0x380 mm/page_alloc.c:5427 __free_slab+0xcf/0x190 mm/slub.c:1894 free_slab mm/slub.c:1909 [inline] discard_slab mm/slub.c:1915 [inline] unfreeze_partials+0x15f/0x190 mm/slub.c:2410 put_cpu_partial+0xc1/0x180 mm/slub.c:2446 __slab_free+0x2c9/0x3a0 mm/slub.c:3095 do_slab_free mm/slub.c:3191 [inline] ___cache_free+0x111/0x130 mm/slub.c:3210 qlink_free+0x50/0x90 mm/kasan/quarantine.c:157 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176 kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283 __kasan_slab_alloc+0x2f/0xf0 mm/kasan/common.c:440 kasan_slab_alloc include/linux/kasan.h:244 [inline] slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:583 slab_alloc_node mm/slub.c:2947 [inline] slab_alloc mm/slub.c:2955 [inline] kmem_cache_alloc+0x165/0x2e0 mm/slub.c:2960 vm_area_dup+0x26/0x250 kernel/fork.c:366 __split_vma+0xbd/0x420 mm/mmap.c:2860 __do_munmap+0x3c3/0x850 mm/mmap.c:2986 Memory state around the buggy address: ffff88810bb6cd80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88810bb6ce00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88810bb6ce80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88810bb6cf00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88810bb6cf80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== ---------------- Code disassembly (best guess): 0: 75 d0 jne 0xffffffd2 2: 4c 8b 6d c0 mov -0x40(%rbp),%r13 6: 74 08 je 0x10 8: 4c 89 e7 mov %r12,%rdi b: e8 98 de 6e 00 call 0x6edea8 10: 49 8b 04 24 mov (%r12),%rax 14: eb 38 jmp 0x4e 16: 65 48 8b 05 9a c7 d3 mov %gs:0x7ed3c79a(%rip),%rax # 0x7ed3c7b8 1d: 7e 1e: 48 39 45 a8 cmp %rax,-0x58(%rbp) 22: 4c 8b 75 d0 mov -0x30(%rbp),%r14 26: 4c 8b 6d c0 mov -0x40(%rbp),%r13 * 2a: 74 0a je 0x36 <-- trapping instruction 2c: 4c 89 ff mov %r15,%rdi 2f: e8 54 03 00 00 call 0x388 34: eb 18 jmp 0x4e 36: 4c 89 f8 mov %r15,%rax 39: 48 c1 e8 03 shr $0x3,%rax 3d: 80 .byte 0x80 3e: 3c 10 cmp $0x10,%al