================================================================== BUG: KASAN: use-after-free in tw_timer_handler+0x8f/0xf0 include/net/net_namespace.h:-1 Read of size 8 at addr ffff888124e661d0 by task swapper/0/0 CPU: 0 PID: 0 Comm: swapper/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 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:ffffffff86207d58 EFLAGS: 00000246 RAX: ffff8881f7000000 RBX: ffffffff8621c040 RCX: 0000000000074142 RDX: 0000000000000001 RSI: ffffffff852010a0 RDI: ffffffff85201060 RBP: ffffffff86207d58 R08: dffffc0000000000 R09: ffffed103ee0ae7b R10: ffffed103ee0ae7b R11: 1ffff1103ee0ae7a R12: 0000000000000000 R13: 1ffffffff0c43808 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 rest_init+0xe8/0xf0 init/main.c:714 arch_call_rest_init+0xe/0x10 init/main.c:839 start_kernel+0x42e/0x49c init/main.c:1041 x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:519 x86_64_start_kernel+0x60/0x63 arch/x86/kernel/head64.c:500 secondary_startup_64_no_verify+0xad/0xbb Allocated by task 278: 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 301: 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 ffff888124e66040 which belongs to the cache net_namespace of size 4672 The buggy address is located 400 bytes inside of 4672-byte region [ffff888124e66040, ffff888124e67280) The buggy address belongs to the page: page:ffffea0004939800 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888124e60000 pfn:0x124e60 head:ffffea0004939800 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head) raw: 4000000000010200 0000000000000000 0000000100000001 ffff888107fdc600 raw: ffff888124e60000 0000000080060005 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 276, ts 21788156869, free_ts 0 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_owner free stack trace missing Memory state around the buggy address: ffff888124e66080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888124e66100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888124e66180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888124e66200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888124e66280: 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