================================================================== BUG: KASAN: use-after-free in tw_timer_handler+0x8f/0xf0 include/net/net_namespace.h:-1 Read of size 8 at addr ffff888128c12810 by task syz.0.4835/10169 CPU: 1 PID: 10169 Comm: syz.0.4835 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:instrument_atomic_read include/linux/instrumented.h:71 [inline] RIP: 0010:atomic64_read include/asm-generic/atomic-instrumented.h:837 [inline] RIP: 0010:atomic_long_read include/asm-generic/atomic-long.h:29 [inline] RIP: 0010:__mutex_owner kernel/locking/mutex.c:77 [inline] RIP: 0010:mutex_spin_on_owner+0x230/0x2e0 kernel/locking/mutex.c:571 Code: 00 00 e8 93 b5 52 00 48 8b 45 a0 42 80 3c 38 00 74 08 4c 89 ef e8 a0 b3 52 00 49 f7 45 00 01 00 00 00 0f 85 8b 00 00 00 f3 90 <4c> 89 ef be 08 00 00 00 e8 63 b5 52 00 48 8b 45 a0 42 80 3c 38 00 RSP: 0018:ffffc90000f87260 EFLAGS: 00000246 RAX: ffff8881f7000000 RBX: ffff888115070000 RCX: ffffffff814acfc9 RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000000 RBP: ffffc90000f872f0 R08: dffffc0000000000 R09: ffffed1023587769 R10: ffffed1023587769 R11: 1ffff11023587768 R12: ffffffff868f59b0 R13: ffffffff868f59a0 R14: ffffffff868f59b0 R15: dffffc0000000000 mutex_optimistic_spin kernel/locking/mutex.c:688 [inline] __mutex_lock_common kernel/locking/mutex.c:976 [inline] __mutex_lock+0x2be/0xc50 kernel/locking/mutex.c:1117 __mutex_lock_slowpath+0xe/0x10 kernel/locking/mutex.c:1379 mutex_lock+0xcf/0xe0 kernel/locking/mutex.c:299 genl_lock net/netlink/genetlink.c:33 [inline] genl_rcv_msg+0x12d/0x1090 net/netlink/genetlink.c:798 netlink_rcv_skb+0x1e0/0x430 net/netlink/af_netlink.c:2485 genl_rcv+0x28/0x40 net/netlink/genetlink.c:811 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 RIP: 0033:0x7f5981e57929 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:00007f59818c8038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f598207efa0 RCX: 00007f5981e57929 RDX: 0000000000000000 RSI: 00002000000001c0 RDI: 0000000000000004 RBP: 00007f5981ed9b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f598207efa0 R15: 00007ffca505c398 Allocated by task 352: 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 The buggy address belongs to the object at ffff888128c12680 which belongs to the cache net_namespace of size 4672 The buggy address is located 400 bytes inside of 4672-byte region [ffff888128c12680, ffff888128c138c0) The buggy address belongs to the page: page:ffffea0004a30400 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888128c12680 pfn:0x128c10 head:ffffea0004a30400 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head) raw: 4000000000010200 ffffea000498b600 0000000200000002 ffff888107fdd800 raw: ffff888128c12680 0000000080060000 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 323, ts 30767217477, free_ts 30751480220 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 get_signal+0xf7d/0x12e0 kernel/signal.c:2793 arch_do_signal_or_restart+0xbf/0x10f0 arch/x86/kernel/signal.c:805 handle_signal_work kernel/entry/common.c:145 [inline] exit_to_user_mode_loop+0xa2/0xe0 kernel/entry/common.c:169 exit_to_user_mode_prepare kernel/entry/common.c:199 [inline] syscall_exit_to_user_mode+0x68/0x90 kernel/entry/common.c:274 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56 entry_SYSCALL_64_after_hwframe+0x61/0xcb Memory state around the buggy address: ffff888128c12700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888128c12780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888128c12800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888128c12880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888128c12900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== ---------------- Code disassembly (best guess): 0: 00 00 add %al,(%rax) 2: e8 93 b5 52 00 call 0x52b59a 7: 48 8b 45 a0 mov -0x60(%rbp),%rax b: 42 80 3c 38 00 cmpb $0x0,(%rax,%r15,1) 10: 74 08 je 0x1a 12: 4c 89 ef mov %r13,%rdi 15: e8 a0 b3 52 00 call 0x52b3ba 1a: 49 f7 45 00 01 00 00 testq $0x1,0x0(%r13) 21: 00 22: 0f 85 8b 00 00 00 jne 0xb3 28: f3 90 pause * 2a: 4c 89 ef mov %r13,%rdi <-- trapping instruction 2d: be 08 00 00 00 mov $0x8,%esi 32: e8 63 b5 52 00 call 0x52b59a 37: 48 8b 45 a0 mov -0x60(%rbp),%rax 3b: 42 80 3c 38 00 cmpb $0x0,(%rax,%r15,1)