syzbot

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BUG: KASAN: use-after-free in sk_psock_unlink+0x370/0x440 net/core/sock_map.c:997
Read of size 4 at addr ffff8880a1ad3c18 by task syz-executor.4/28949

CPU: 0 PID: 28949 Comm: syz-executor.4 Not tainted 5.3.0-rc6-next-20190830 #75
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:634
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:131
 sk_psock_unlink+0x370/0x440 net/core/sock_map.c:997
 tcp_bpf_remove+0x21/0x50 net/ipv4/tcp_bpf.c:539
 tcp_bpf_close+0x130/0x390 net/ipv4/tcp_bpf.c:579
 tls_sk_proto_close+0x35b/0x990 net/tls/tls_main.c:321
 inet_release+0xed/0x200 net/ipv4/af_inet.c:427
 inet6_release+0x53/0x80 net/ipv6/af_inet6.c:470
 __sock_release+0xce/0x280 net/socket.c:590
 sock_close+0x1e/0x30 net/socket.c:1268
 __fput+0x2ff/0x890 fs/file_table.c:280
 ____fput+0x16/0x20 fs/file_table.c:313
 task_work_run+0x145/0x1c0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:163
 prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:274 [inline]
 do_syscall_64+0x65f/0x760 arch/x86/entry/common.c:300
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413540
Code: 01 f0 ff ff 0f 83 30 1b 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 83 3d 4d 2d 66 00 00 75 14 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff
RSP: 002b:00007fff5ef1cc98 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000006 RCX: 0000000000413540
RDX: 0000001b2d020000 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffffffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bf20
R13: 0000000000000005 R14: 0000000000761178 R15: ffffffffffffffff

Allocated by task 28949:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc mm/kasan/common.c:510 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:483
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:524
 kmem_cache_alloc_trace+0x158/0x790 mm/slab.c:3550
 kmalloc include/linux/slab.h:556 [inline]
 kzalloc include/linux/slab.h:690 [inline]
 sock_hash_alloc net/core/sock_map.c:806 [inline]
 sock_hash_alloc+0x1e3/0x5b0 net/core/sock_map.c:790
 find_and_alloc_map kernel/bpf/syscall.c:121 [inline]
 map_create kernel/bpf/syscall.c:569 [inline]
 __do_sys_bpf+0x475/0x3350 kernel/bpf/syscall.c:2848
 __se_sys_bpf kernel/bpf/syscall.c:2825 [inline]
 __x64_sys_bpf+0x73/0xb0 kernel/bpf/syscall.c:2825
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8745:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 kasan_set_free_info mm/kasan/common.c:332 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:471
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:480
 __cache_free mm/slab.c:3425 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3756
 sock_hash_free+0x327/0x4a0 net/core/sock_map.c:869
 bpf_map_free_deferred+0xb3/0x100 kernel/bpf/syscall.c:307
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff8880a1ad3c00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 24 bytes inside of
 512-byte region [ffff8880a1ad3c00, ffff8880a1ad3e00)
The buggy address belongs to the page:
page:ffffea000286b4c0 refcount:1 mapcount:0 mapping:ffff8880aa400a80 index:0xffff8880a1ad3400
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea000262b208 ffffea0002970d88 ffff8880aa400a80
raw: ffff8880a1ad3400 ffff8880a1ad3000 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a1ad3b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a1ad3b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a1ad3c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff8880a1ad3c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a1ad3d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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