=====================================================
BUG: KMSAN: uninit-value in __flush_smp_call_function_queue+0x343/0x1810 kernel/smp.c:549
 __flush_smp_call_function_queue+0x343/0x1810 kernel/smp.c:549
 generic_smp_call_function_single_interrupt+0x1c/0x30 kernel/smp.c:477
 __sysvec_call_function_single+0x48/0x350 arch/x86/kernel/smp.c:272
 instr_sysvec_call_function_single arch/x86/kernel/smp.c:267 [inline]
 sysvec_call_function_single+0x7c/0x90 arch/x86/kernel/smp.c:267
 asm_sysvec_call_function_single+0x1f/0x30 arch/x86/include/asm/idtentry.h:704
 kmsan_get_shadow_origin_ptr+0x4a/0xb0 mm/kmsan/shadow.c:102
 get_shadow_origin_ptr mm/kmsan/instrumentation.c:38 [inline]
 __msan_metadata_ptr_for_load_8+0x24/0x40 mm/kmsan/instrumentation.c:94
 unwind_get_return_address_ptr+0x9b/0xd0 arch/x86/kernel/unwind_frame.c:28
 update_stack_state+0x174/0x1c0 arch/x86/kernel/unwind_frame.c:251
 unwind_next_frame+0x116/0x350 arch/x86/kernel/unwind_frame.c:315
 arch_stack_walk+0x1b0/0x280 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xc2/0x100 kernel/stacktrace.c:122
 kmsan_save_stack_with_flags mm/kmsan/core.c:73 [inline]
 kmsan_internal_poison_memory+0x4a/0x90 mm/kmsan/core.c:57
 kmsan_slab_alloc+0xdc/0x160 mm/kmsan/hooks.c:66
 slab_post_alloc_hook mm/slub.c:4577 [inline]
 slab_alloc_node mm/slub.c:4899 [inline]
 kmem_cache_alloc_node_noprof+0x3cd/0x12c0 mm/slub.c:4951
 kmalloc_reserve net/core/skbuff.c:613 [inline]
 __alloc_skb+0x855/0x1190 net/core/skbuff.c:713
 alloc_skb include/linux/skbuff.h:1385 [inline]
 nlmsg_new include/net/netlink.h:1055 [inline]
 rtmsg_fib+0x135/0x690 net/ipv4/fib_semantics.c:551
 fib_table_delete+0x176f/0x1af0 net/ipv4/fib_trie.c:1740
 fib_magic+0x45a/0x5c0 net/ipv4/fib_frontend.c:1136
 fib_del_ifaddr+0x206b/0x2660 net/ipv4/fib_frontend.c:1347
 fib_inetaddr_event+0xc7/0x590 net/ipv4/fib_frontend.c:1478
 notifier_call_chain kernel/notifier.c:85 [inline]
 blocking_notifier_call_chain+0x129/0x4c0 kernel/notifier.c:380
 __inet_del_ifa+0x12be/0x19d0 net/ipv4/devinet.c:450
 inet_del_ifa net/ipv4/devinet.c:487 [inline]
 inetdev_destroy net/ipv4/devinet.c:328 [inline]
 inetdev_event+0x1737/0x24b0 net/ipv4/devinet.c:1655
 notifier_call_chain kernel/notifier.c:85 [inline]
 raw_notifier_call_chain+0xe6/0x450 kernel/notifier.c:453
 call_netdevice_notifiers_info net/core/dev.c:2249 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
 call_netdevice_notifiers net/core/dev.c:2301 [inline]
 unregister_netdevice_many_notify+0x2ec6/0x4a60 net/core/dev.c:12421
 unregister_netdevice_many net/core/dev.c:12484 [inline]
 default_device_exit_batch+0x1061/0x1120 net/core/dev.c:13076
 ops_exit_list net/core/net_namespace.c:205 [inline]
 ops_undo_list+0x7e0/0xb80 net/core/net_namespace.c:252
 cleanup_net+0xc24/0x1680 net/core/net_namespace.c:702
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0xb65/0x1e40 kernel/workqueue.c:3397
 worker_thread+0xee4/0x1590 kernel/workqueue.c:3478
 kthread+0x53a/0x5f0 kernel/kthread.c:436
 ret_from_fork+0x20f/0x8d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Local variable rf created at:
 __schedule+0x3a/0x8750 kernel/sched/core.c:7028
 preempt_schedule_irq+0x50/0xa0 kernel/sched/core.c:7513

CPU: 0 UID: 0 PID: 34 Comm: kworker/u8:2 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: netns cleanup_net
=====================================================