syzbot

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BUG: KASAN: use-after-free in atomic_dec include/asm-generic/atomic-instrumented.h:114 [inline]
BUG: KASAN: use-after-free in free_htab_elem+0x23/0x40 kernel/bpf/sockmap.c:224
Write of size 4 at addr ffff8801bd745448 by task syz-executor0/6885

CPU: 1 PID: 6885 Comm: syz-executor0 Not tainted 4.18.0-rc2+ #44
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+0x1c9/0x2b4 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 kasan_check_write+0x14/0x20 mm/kasan/kasan.c:278
 atomic_dec include/asm-generic/atomic-instrumented.h:114 [inline]
 free_htab_elem+0x23/0x40 kernel/bpf/sockmap.c:224
 bpf_tcp_close+0x8c9/0xfa0 kernel/bpf/sockmap.c:273
 inet_release+0x104/0x1f0 net/ipv4/af_inet.c:427
 inet6_release+0x50/0x70 net/ipv6/af_inet6.c:459
 __sock_release+0xd7/0x260 net/socket.c:603
 sock_close+0x19/0x20 net/socket.c:1186
 __fput+0x35b/0x8b0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x1ec/0x2a0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x1b08/0x2750 kernel/exit.c:865
 do_group_exit+0x177/0x440 kernel/exit.c:968
 get_signal+0x88e/0x1970 kernel/signal.c:2468
 do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816
 exit_to_usermode_loop+0x2e0/0x370 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455ab9
Code: 1d ba fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 eb b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 
RSP: 002b:00007fe4b0235ce8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000072c010 RCX: 0000000000455ab9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000072c010
RBP: 000000000072c010 R08: 0000000000000000 R09: 000000000072bff0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffdbe58820f R14: 00007fe4b02369c0 R15: 0000000000000002

Allocated by task 6866:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620
 kmalloc include/linux/slab.h:513 [inline]
 kzalloc include/linux/slab.h:707 [inline]
 sock_hash_alloc+0x20d/0x6a0 kernel/bpf/sockmap.c:2003
 find_and_alloc_map kernel/bpf/syscall.c:129 [inline]
 map_create+0x39b/0x1020 kernel/bpf/syscall.c:453
 __do_sys_bpf kernel/bpf/syscall.c:2345 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:2322 [inline]
 __x64_sys_bpf+0x303/0x510 kernel/bpf/syscall.c:2322
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 26:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kfree+0xd9/0x260 mm/slab.c:3813
 sock_hash_free+0x524/0x6f0 kernel/bpf/sockmap.c:2098
 bpf_map_free_deferred+0xba/0xf0 kernel/bpf/syscall.c:262
 process_one_work+0xc73/0x1ba0 kernel/workqueue.c:2153
 worker_thread+0x189/0x13c0 kernel/workqueue.c:2296
 kthread+0x345/0x410 kernel/kthread.c:240
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

The buggy address belongs to the object at ffff8801bd745340
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 264 bytes inside of
 512-byte region [ffff8801bd745340, ffff8801bd745540)
The buggy address belongs to the page:
page:ffffea0006f5d140 count:1 mapcount:0 mapping:ffff8801da800940 index:0xffff8801bd745d40
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea00073dba88 ffffea0006a6a408 ffff8801da800940
raw: ffff8801bd745d40 ffff8801bd7450c0 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801bd745300: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff8801bd745380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801bd745400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff8801bd745480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801bd745500: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
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