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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 ffff8880834d2368 by task syz-executor.1/3643

CPU: 1 PID: 3643 Comm: syz-executor.1 Not tainted 6.1.0-rc3-syzkaller-00152-gf2f32f8af2b0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
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:284 [inline]
 print_report+0x15e/0x461 mm/kasan/report.c:395
 kasan_report+0xbb/0x1f0 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:10237 [inline]
 netdev_run_todo+0xbc2/0x1100 net/core/dev.c:10351
 tun_detach drivers/net/tun.c:704 [inline]
 tun_chr_close+0xe0/0x180 drivers/net/tun.c:3459
 __fput+0x27c/0xa90 fs/file_table.c:320
 task_work_run+0x16b/0x270 kernel/task_work.c:179
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0xb35/0x2a20 kernel/exit.c:820
 do_group_exit+0xd0/0x2a0 kernel/exit.c:950
 __do_sys_exit_group kernel/exit.c:961 [inline]
 __se_sys_exit_group kernel/exit.c:959 [inline]
 __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:959
 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
RIP: 0033:0x7f67d5c8b5a9
Code: Unable to access opcode bytes at 0x7f67d5c8b57f.
RSP: 002b:00007ffd40c5ebd8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007ffd40c5f460 RCX: 00007f67d5c8b5a9
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000043
RBP: 0000000000000000 R08: 0000000000000026 R09: 00007ffd40c5f460
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f67d5cd57f0
R13: 0000000000000002 R14: 0000000000000005 R15: 00007ffd40c5f4a0
 </TASK>

Allocated by task 3643:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45
 kasan_set_track+0x21/0x30 mm/kasan/common.c:52
 __kasan_slab_alloc+0x7b/0x80 mm/kasan/common.c:325
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook mm/slab.h:737 [inline]
 slab_alloc_node mm/slab.c:3257 [inline]
 slab_alloc mm/slab.c:3265 [inline]
 __kmem_cache_alloc_lru mm/slab.c:3442 [inline]
 kmem_cache_alloc+0x218/0x450 mm/slab.c:3461
 kmem_cache_zalloc include/linux/slab.h:702 [inline]
 net_alloc net/core/net_namespace.c:410 [inline]
 copy_net_ns+0x125/0x760 net/core/net_namespace.c:465
 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:226
 ksys_unshare+0x445/0x920 kernel/fork.c:3188
 __do_sys_unshare kernel/fork.c:3259 [inline]
 __se_sys_unshare kernel/fork.c:3257 [inline]
 __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3257
 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 21297:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45
 kasan_set_track+0x21/0x30 mm/kasan/common.c:52
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:511
 ____kasan_slab_free mm/kasan/common.c:236 [inline]
 ____kasan_slab_free+0x13b/0x1a0 mm/kasan/common.c:200
 kasan_slab_free include/linux/kasan.h:177 [inline]
 __cache_free mm/slab.c:3389 [inline]
 __do_kmem_cache_free mm/slab.c:3585 [inline]
 kmem_cache_free mm/slab.c:3610 [inline]
 kmem_cache_free+0x104/0x4b0 mm/slab.c:3603
 net_free net/core/net_namespace.c:439 [inline]
 net_free net/core/net_namespace.c:435 [inline]
 cleanup_net+0x8ba/0xb00 net/core/net_namespace.c:622
 process_one_work+0x9bf/0x1710 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:45
 __kasan_record_aux_stack+0x7b/0x90 mm/kasan/generic.c:481
 insert_work+0x48/0x350 kernel/workqueue.c:1358
 __queue_work+0x693/0x13b0 kernel/workqueue.c:1517
 call_timer_fn+0x1da/0x7c0 kernel/time/timer.c:1474
 expire_timers kernel/time/timer.c:1514 [inline]
 __run_timers.part.0+0x4a3/0xaf0 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+0x1f7/0xad8 kernel/softirq.c:571

Second to last potentially related work creation:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45
 __kasan_record_aux_stack+0x7b/0x90 mm/kasan/generic.c:481
 insert_work+0x48/0x350 kernel/workqueue.c:1358
 __queue_work+0x693/0x13b0 kernel/workqueue.c:1517
 call_timer_fn+0x1da/0x7c0 kernel/time/timer.c:1474
 expire_timers kernel/time/timer.c:1514 [inline]
 __run_timers.part.0+0x4a3/0xaf0 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+0x1f7/0xad8 kernel/softirq.c:571

The buggy address belongs to the object at ffff8880834d2100
 which belongs to the cache net_namespace of size 6976
The buggy address is located 616 bytes inside of
 6976-byte region [ffff8880834d2100, ffff8880834d3c40)

The buggy address belongs to the physical page:
page:ffffea00020d3480 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x834d2
head:ffffea00020d3480 order:1 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffffea00020d3308 ffffea00020db888 ffff88814008ff00
raw: 0000000000000000 ffff8880834d2100 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 0x2420c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_COMP|__GFP_THISNODE), pid 3643, tgid 3643 (syz-executor.1), ts 246315632616, free_ts 0
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x10b5/0x2d50 mm/page_alloc.c:4288
 __alloc_pages+0x1c7/0x5a0 mm/page_alloc.c:5555
 __alloc_pages_node include/linux/gfp.h:223 [inline]
 kmem_getpages mm/slab.c:1363 [inline]
 cache_grow_begin+0x75/0x360 mm/slab.c:2570
 cache_alloc_refill+0x27f/0x380 mm/slab.c:2943
 ____cache_alloc mm/slab.c:3019 [inline]
 ____cache_alloc mm/slab.c:3002 [inline]
 __do_cache_alloc mm/slab.c:3202 [inline]
 slab_alloc_node mm/slab.c:3250 [inline]
 slab_alloc mm/slab.c:3265 [inline]
 __kmem_cache_alloc_lru mm/slab.c:3442 [inline]
 kmem_cache_alloc+0x35c/0x450 mm/slab.c:3461
 kmem_cache_zalloc include/linux/slab.h:702 [inline]
 net_alloc net/core/net_namespace.c:410 [inline]
 copy_net_ns+0x125/0x760 net/core/net_namespace.c:465
 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:226
 ksys_unshare+0x445/0x920 kernel/fork.c:3188
 __do_sys_unshare kernel/fork.c:3259 [inline]
 __se_sys_unshare kernel/fork.c:3257 [inline]
 __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3257
 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:
 ffff8880834d2200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880834d2280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880834d2300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                          ^
 ffff8880834d2380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880834d2400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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