================================================================== BUG: KASAN: use-after-free in tw_timer_handler+0x8f/0xf0 include/net/net_namespace.h:-1 Read of size 8 at addr ffff888121618190 by task swapper/1/0 CPU: 1 PID: 0 Comm: swapper/1 Tainted: G W 5.10.238-syzkaller-00282-gd76d4cd0623a #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 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:default_idle+0x12/0x20 arch/x86/kernel/process.c:712 Code: 48 8b 7c 24 10 e8 6e 29 00 00 e9 71 ff ff ff e8 94 00 fb ff 00 00 cc cc 55 48 89 e5 0f 1f 44 00 00 0f 00 2d 60 4d 50 00 fb f4 <5d> c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 55 48 89 e5 41 57 41 56 RSP: 0018:ffffc90000107d98 EFLAGS: 00000242 RAX: ffff8881f7100000 RBX: ffff888100294f00 RCX: 000000000003a562 RDX: 0000000000000001 RSI: ffffffff852010a0 RDI: ffffffff85201060 RBP: ffffc90000107d98 R08: dffffc0000000000 R09: ffffed103ee2ae7b R10: ffffed103ee2ae7b R11: 1ffff1103ee2ae7a R12: 0000000000000001 R13: 1ffff110200529e0 R14: 0000000000000000 R15: dffffc0000000000 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:703 default_idle_call+0x71/0x1d0 kernel/sched/idle.c:114 cpuidle_idle_call kernel/sched/idle.c:196 [inline] do_idle+0x1df/0x530 kernel/sched/idle.c:308 cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:404 start_secondary+0x2e9/0x3a0 arch/x86/kernel/smpboot.c:276 secondary_startup_64_no_verify+0xad/0xbb Allocated by task 993: 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 881: 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 Last potentially related work creation: kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38 __kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358 insert_work+0x52/0x310 kernel/workqueue.c:1352 __queue_work+0x923/0xca0 kernel/workqueue.c:1518 queue_work_on+0xd5/0x130 kernel/workqueue.c:1545 queue_work include/linux/workqueue.h:515 [inline] schedule_work include/linux/workqueue.h:576 [inline] xfrm_policy_hash_rebuild+0x4f/0x60 net/xfrm/xfrm_policy.c:1366 xfrm_set_spdinfo+0x3f6/0x5e0 net/xfrm/xfrm_user.c:1246 xfrm_user_rcv_msg+0x450/0x6d0 net/xfrm/xfrm_user.c:2789 netlink_rcv_skb+0x1e0/0x430 net/netlink/af_netlink.c:2485 xfrm_netlink_rcv+0x72/0x90 net/xfrm/xfrm_user.c:2811 netlink_unicast_kernel net/netlink/af_netlink.c:1307 [inline] netlink_unicast+0x87c/0xa40 net/netlink/af_netlink.c:1333 netlink_sendmsg+0x88d/0xb30 net/netlink/af_netlink.c:1901 sock_sendmsg_nosec net/socket.c:652 [inline] __sock_sendmsg net/socket.c:664 [inline] ____sys_sendmsg+0x5a2/0x8c0 net/socket.c:2376 ___sys_sendmsg+0x1f0/0x260 net/socket.c:2430 __sys_sendmsg net/socket.c:2459 [inline] __do_sys_sendmsg net/socket.c:2468 [inline] __se_sys_sendmsg net/socket.c:2466 [inline] __x64_sys_sendmsg+0x1e2/0x2a0 net/socket.c:2466 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb The buggy address belongs to the object at ffff888121618000 which belongs to the cache net_namespace of size 4672 The buggy address is located 400 bytes inside of 4672-byte region [ffff888121618000, ffff888121619240) The buggy address belongs to the page: page:ffffea0004858600 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88812161b9c0 pfn:0x121618 head:ffffea0004858600 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head) raw: 4000000000010200 ffffea0004988608 ffff888107fa7b10 ffff888107fdc480 raw: ffff88812161b9c0 0000000000060002 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 938, ts 49024084144, free_ts 48943650745 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 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 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_pcp_prepare mm/page_alloc.c:1421 [inline] free_unref_page_prepare+0x2b7/0x2d0 mm/page_alloc.c:3336 free_unref_page mm/page_alloc.c:3391 [inline] free_the_page mm/page_alloc.c:5416 [inline] __free_pages+0x14b/0x380 mm/page_alloc.c:5427 __vunmap+0x84d/0x9d0 mm/vmalloc.c:2301 __vfree mm/vmalloc.c:2350 [inline] vfree+0x61/0x90 mm/vmalloc.c:2381 kcov_put kernel/kcov.c:408 [inline] kcov_close+0x2b/0x50 kernel/kcov.c:510 __fput+0x2fb/0x770 fs/file_table.c:281 ____fput+0x15/0x20 fs/file_table.c:314 task_work_run+0x127/0x190 kernel/task_work.c:189 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0xa27/0x2470 kernel/exit.c:863 do_group_exit+0x141/0x310 kernel/exit.c:985 __do_sys_exit_group kernel/exit.c:996 [inline] __se_sys_exit_group kernel/exit.c:994 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:994 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x61/0xcb Memory state around the buggy address: ffff888121618080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888121618100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888121618180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888121618200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888121618280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== ---------------- Code disassembly (best guess): 0: 48 8b 7c 24 10 mov 0x10(%rsp),%rdi 5: e8 6e 29 00 00 call 0x2978 a: e9 71 ff ff ff jmp 0xffffff80 f: e8 94 00 fb ff call 0xfffb00a8 14: 00 00 add %al,(%rax) 16: cc int3 17: cc int3 18: 55 push %rbp 19: 48 89 e5 mov %rsp,%rbp 1c: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 21: 0f 00 2d 60 4d 50 00 verw 0x504d60(%rip) # 0x504d88 28: fb sti 29: f4 hlt * 2a: 5d pop %rbp <-- trapping instruction 2b: c3 ret 2c: 66 2e 0f 1f 84 00 00 cs nopw 0x0(%rax,%rax,1) 33: 00 00 00 36: 66 90 xchg %ax,%ax 38: 55 push %rbp 39: 48 89 e5 mov %rsp,%rbp 3c: 41 57 push %r15 3e: 41 56 push %r14