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BUG: KASAN: use-after-free in notifier_call_chain+0x1ee/0x200 kernel/notifier.c:75
Read of size 8 at addr ffff8880749b62e8 by task syz-executor.0/26057

CPU: 3 PID: 26057 Comm: syz-executor.0 Not tainted 6.0.0-rc4-syzkaller-00302-gb96fbd602d35 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:317 [inline]
 print_report.cold+0x2ba/0x6e9 mm/kasan/report.c:433
 kasan_report+0xb1/0x1e0 mm/kasan/report.c:495
 notifier_call_chain+0x1ee/0x200 kernel/notifier.c:75
 call_netdevice_notifiers_info+0x86/0x130 net/core/dev.c:1942
 call_netdevice_notifiers_extack net/core/dev.c:1983 [inline]
 call_netdevice_notifiers net/core/dev.c:1997 [inline]
 netdev_wait_allrefs_any net/core/dev.c:10250 [inline]
 netdev_run_todo+0xbc2/0x1100 net/core/dev.c:10364
 tun_detach drivers/net/tun.c:704 [inline]
 tun_chr_close+0xe0/0x180 drivers/net/tun.c:3455
 __fput+0x277/0x9d0 fs/file_table.c:320
 task_work_run+0xdd/0x1a0 kernel/task_work.c:177
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0xad5/0x29b0 kernel/exit.c:795
 do_group_exit+0xd2/0x2f0 kernel/exit.c:925
 get_signal+0x238c/0x2610 kernel/signal.c:2857
 arch_do_signal_or_restart+0x82/0x2300 arch/x86/kernel/signal.c:869
 exit_to_user_mode_loop kernel/entry/common.c:166 [inline]
 exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
 syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:294
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7ff7612893c9
Code: Unable to access opcode bytes at RIP 0x7ff76128939f.
RSP: 002b:00007ff7624c4168 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: fffffffffffffff4 RBX: 00007ff76139bf80 RCX: 00007ff7612893c9
RDX: 0000000000000048 RSI: 00000000200003c0 RDI: 0000000000000000
RBP: 00007ff7612e433f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffea50245ef R14: 00007ff7624c4300 R15: 0000000000022000
 </TASK>

Allocated by task 3728:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:437 [inline]
 __kasan_slab_alloc+0x85/0xb0 mm/kasan/common.c:470
 kasan_slab_alloc include/linux/kasan.h:224 [inline]
 slab_post_alloc_hook mm/slab.h:727 [inline]
 slab_alloc mm/slab.c:3294 [inline]
 __kmem_cache_alloc_lru mm/slab.c:3471 [inline]
 kmem_cache_alloc+0x214/0x520 mm/slab.c:3491
 kmem_cache_zalloc include/linux/slab.h:723 [inline]
 net_alloc net/core/net_namespace.c:404 [inline]
 copy_net_ns+0x125/0x760 net/core/net_namespace.c:459
 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:227
 ksys_unshare+0x445/0x920 kernel/fork.c:3184
 __do_sys_unshare kernel/fork.c:3255 [inline]
 __se_sys_unshare kernel/fork.c:3253 [inline]
 __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3253
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 10:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track+0x21/0x30 mm/kasan/common.c:45
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
 ____kasan_slab_free mm/kasan/common.c:367 [inline]
 ____kasan_slab_free+0x13d/0x1a0 mm/kasan/common.c:329
 kasan_slab_free include/linux/kasan.h:200 [inline]
 __cache_free mm/slab.c:3418 [inline]
 kmem_cache_free.part.0+0x10f/0x2e0 mm/slab.c:3725
 net_free net/core/net_namespace.c:433 [inline]
 net_free net/core/net_namespace.c:429 [inline]
 cleanup_net+0x8ba/0xb00 net/core/net_namespace.c:616
 process_one_work+0x991/0x1610 kernel/workqueue.c:2289
 worker_thread+0x665/0x1080 kernel/workqueue.c:2436
 kthread+0x2e4/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

Last potentially related work creation:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 __kasan_record_aux_stack+0x7e/0x90 mm/kasan/generic.c:348
 insert_work+0x48/0x350 kernel/workqueue.c:1358
 __queue_work+0x625/0x1210 kernel/workqueue.c:1517
 call_timer_fn+0x1a0/0x6b0 kernel/time/timer.c:1474
 expire_timers kernel/time/timer.c:1514 [inline]
 __run_timers.part.0+0x4a3/0xa80 kernel/time/timer.c:1790
 __run_timers kernel/time/timer.c:1768 [inline]
 run_timer_softirq+0x152/0x1d0 kernel/time/timer.c:1805
 __do_softirq+0x1d3/0x9c6 kernel/softirq.c:571

Second to last potentially related work creation:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 __kasan_record_aux_stack+0x7e/0x90 mm/kasan/generic.c:348
 insert_work+0x48/0x350 kernel/workqueue.c:1358
 __queue_work+0x625/0x1210 kernel/workqueue.c:1517
 call_timer_fn+0x1a0/0x6b0 kernel/time/timer.c:1474
 expire_timers kernel/time/timer.c:1514 [inline]
 __run_timers.part.0+0x4a3/0xa80 kernel/time/timer.c:1790
 __run_timers kernel/time/timer.c:1768 [inline]
 run_timer_softirq+0x152/0x1d0 kernel/time/timer.c:1805
 __do_softirq+0x1d3/0x9c6 kernel/softirq.c:571

The buggy address belongs to the object at ffff8880749b6080
 which belongs to the cache net_namespace of size 6784
The buggy address is located 616 bytes inside of
 6784-byte region [ffff8880749b6080, ffff8880749b7b00)

The buggy address belongs to the physical page:
page:ffffea0001d26d80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x749b6
head:ffffea0001d26d80 order:1 compound_mapcount:0 compound_pincount:0
flags: 0x4fff00000010200(slab|head|node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff00000010200 ffffea0001d12688 ffffea0001d37b08 ffff8880121e1400
raw: 0000000000000000 ffff8880749b6080 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0x40cc0(GFP_KERNEL|__GFP_COMP), pid 3728, tgid 3728 (syz-executor.0), ts 250744189262, free_ts 0
 prep_new_page mm/page_alloc.c:2532 [inline]
 get_page_from_freelist+0x109b/0x2ce0 mm/page_alloc.c:4283
 __alloc_pages+0x1c7/0x510 mm/page_alloc.c:5515
 __alloc_pages_node include/linux/gfp.h:243 [inline]
 kmem_getpages mm/slab.c:1363 [inline]
 cache_grow_begin+0x75/0x360 mm/slab.c:2569
 fallback_alloc+0x1e2/0x2d0 mm/slab.c:3112
 __do_cache_alloc mm/slab.c:3253 [inline]
 slab_alloc mm/slab.c:3287 [inline]
 __kmem_cache_alloc_lru mm/slab.c:3471 [inline]
 kmem_cache_alloc+0x30d/0x520 mm/slab.c:3491
 kmem_cache_zalloc include/linux/slab.h:723 [inline]
 net_alloc net/core/net_namespace.c:404 [inline]
 copy_net_ns+0x125/0x760 net/core/net_namespace.c:459
 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:227
 ksys_unshare+0x445/0x920 kernel/fork.c:3184
 __do_sys_unshare kernel/fork.c:3255 [inline]
 __se_sys_unshare kernel/fork.c:3253 [inline]
 __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3253
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8880749b6180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880749b6200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880749b6280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                          ^
 ffff8880749b6300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880749b6380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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