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BUG: KASAN: slab-use-after-free in tcp_ioctl+0x76d/0x860 net/ipv4/tcp.c:678
Read of size 4 at addr ffff8881023c66e4 by task syz.0.21/6017

CPU: 0 UID: 0 PID: 6017 Comm: syz.0.21 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 tcp_ioctl+0x76d/0x860 net/ipv4/tcp.c:678
 sock_ioctl_out net/core/sock.c:4392 [inline]
 sk_ioctl+0x3c7/0x600 net/core/sock.c:4420
 inet_ioctl+0x416/0x4c0 net/ipv4/af_inet.c:1007
 sock_do_ioctl+0xdc/0x300 net/socket.c:1254
 sock_ioctl+0x576/0x790 net/socket.c:1375
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd75e18f749
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:00007fd75f094038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd75e3e5fa0 RCX: 00007fd75e18f749
RDX: 0000200000000080 RSI: 000000000000894b RDI: 0000000000000003
RBP: 00007fd75e213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd75e3e6038 R14: 00007fd75e3e5fa0 R15: 00007ffc97663258
 </TASK>

Allocated by task 5843:
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 unpoison_slab_object mm/kasan/common.c:342 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:368
 kasan_slab_alloc include/linux/kasan.h:252 [inline]
 slab_post_alloc_hook mm/slub.c:4978 [inline]
 slab_alloc_node mm/slub.c:5288 [inline]
 kmem_cache_alloc_noprof+0x367/0x6e0 mm/slub.c:5295
 sk_prot_alloc+0x57/0x220 net/core/sock.c:2233
 sk_alloc+0x3a/0x370 net/core/sock.c:2295
 inet_create+0x7a0/0x1000 net/ipv4/af_inet.c:328
 __sock_create+0x4b3/0x9f0 net/socket.c:1605
 inet_ctl_sock_create+0x9a/0x220 net/ipv4/af_inet.c:1632
 igmp_net_init+0xb9/0x150 net/ipv4/igmp.c:3125
 ops_init+0x35c/0x5c0 net/core/net_namespace.c:137
 setup_net+0xfe/0x320 net/core/net_namespace.c:445
 copy_net_ns+0x34e/0x4e0 net/core/net_namespace.c:580
 create_new_namespaces+0x3f3/0x720 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0x11c/0x170 kernel/nsproxy.c:218
 ksys_unshare+0x4c8/0x8c0 kernel/fork.c:3129
 __do_sys_unshare kernel/fork.c:3200 [inline]
 __se_sys_unshare kernel/fork.c:3198 [inline]
 __x64_sys_unshare+0x38/0x50 kernel/fork.c:3198
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5682:
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 __kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587
 kasan_save_free_info mm/kasan/kasan.h:406 [inline]
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2543 [inline]
 slab_free mm/slub.c:6642 [inline]
 kmem_cache_free+0x19b/0x690 mm/slub.c:6752
 sk_prot_free net/core/sock.c:2276 [inline]
 __sk_destruct+0x4d2/0x660 net/core/sock.c:2373
 inet_release+0x144/0x190 net/ipv4/af_inet.c:437
 __sock_release net/socket.c:662 [inline]
 sock_release+0x85/0x150 net/socket.c:690
 ops_exit_list net/core/net_namespace.c:199 [inline]
 ops_undo_list+0x49a/0x990 net/core/net_namespace.c:252
 cleanup_net+0x4d8/0x820 net/core/net_namespace.c:695
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff8881023c6600
 which belongs to the cache UDP of size 1984
The buggy address is located 228 bytes inside of
 freed 1984-byte region [ffff8881023c6600, ffff8881023c6dc0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1023c0
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888114298b01
anon flags: 0x17ff00000000040(head|node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000040 ffff888104ab6640 0000000000000000 0000000000000001
raw: 0000000000000000 00000000800f000f 00000000f5000000 ffff888114298b01
head: 017ff00000000040 ffff888104ab6640 0000000000000000 0000000000000001
head: 0000000000000000 00000000800f000f 00000000f5000000 ffff888114298b01
head: 017ff00000000003 ffffea000408f001 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
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 1, tgid 1 (swapper/0), ts 4132853290, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1850
 prep_new_page mm/page_alloc.c:1858 [inline]
 get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3884
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5183
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:3059 [inline]
 allocate_slab+0x96/0x350 mm/slub.c:3232
 new_slab mm/slub.c:3286 [inline]
 ___slab_alloc+0xf56/0x1990 mm/slub.c:4655
 __slab_alloc+0x65/0x100 mm/slub.c:4778
 __slab_alloc_node mm/slub.c:4854 [inline]
 slab_alloc_node mm/slub.c:5276 [inline]
 kmem_cache_alloc_noprof+0x3f9/0x6e0 mm/slub.c:5295
 sk_prot_alloc+0x57/0x220 net/core/sock.c:2233
 sk_alloc+0x3a/0x370 net/core/sock.c:2295
 inet_create+0x7a0/0x1000 net/ipv4/af_inet.c:328
 __sock_create+0x4b3/0x9f0 net/socket.c:1605
 inet_ctl_sock_create+0x9a/0x220 net/ipv4/af_inet.c:1632
 igmp_net_init+0xb9/0x150 net/ipv4/igmp.c:3125
 ops_init+0x35c/0x5c0 net/core/net_namespace.c:137
 __register_pernet_operations net/core/net_namespace.c:1314 [inline]
 register_pernet_operations+0x336/0x800 net/core/net_namespace.c:1391
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8881023c6580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881023c6600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881023c6680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff8881023c6700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881023c6780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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