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BUG: KASAN: use-after-free in list_empty include/linux/list.h:282 [inline]
BUG: KASAN: use-after-free in waitqueue_active include/linux/wait.h:127 [inline]
BUG: KASAN: use-after-free in wq_has_sleeper include/linux/wait.h:161 [inline]
BUG: KASAN: use-after-free in skwq_has_sleeper include/net/sock.h:2143 [inline]
BUG: KASAN: use-after-free in sock_def_write_space+0x609/0x630 net/core/sock.c:2926
Read of size 8 at addr ffff888066f03b00 by task syz-executor.4/9262

CPU: 1 PID: 9262 Comm: syz-executor.4 Not tainted 5.8.0-rc6-syzkaller #0
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+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 list_empty include/linux/list.h:282 [inline]
 waitqueue_active include/linux/wait.h:127 [inline]
 wq_has_sleeper include/linux/wait.h:161 [inline]
 skwq_has_sleeper include/net/sock.h:2143 [inline]
 sock_def_write_space+0x609/0x630 net/core/sock.c:2926
 sock_wfree+0x1cc/0x240 net/core/sock.c:2060
 skb_release_head_state+0x9f/0x250 net/core/skbuff.c:651
 skb_release_all net/core/skbuff.c:662 [inline]
 __kfree_skb net/core/skbuff.c:678 [inline]
 kfree_skb.part.0+0x89/0x350 net/core/skbuff.c:696
 kfree_skb+0x7d/0x100 include/linux/refcount.h:270
 skb_queue_purge+0x14/0x30 net/core/skbuff.c:3077
 qrtr_tun_release+0x40/0x60 net/qrtr/tun.c:118
 __fput+0x33c/0x880 fs/file_table.c:281
 task_work_run+0xdd/0x190 kernel/task_work.c:135
 exit_task_work include/linux/task_work.h:25 [inline]
 do_exit+0xb72/0x2a40 kernel/exit.c:805
 do_group_exit+0x125/0x310 kernel/exit.c:903
 get_signal+0x40b/0x1ee0 kernel/signal.c:2743
 do_signal+0x82/0x2520 arch/x86/kernel/signal.c:810
 exit_to_usermode_loop arch/x86/entry/common.c:235 [inline]
 __prepare_exit_to_usermode+0x156/0x1f0 arch/x86/entry/common.c:269
 do_syscall_64+0x6c/0xe0 arch/x86/entry/common.c:393
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45c369
Code: Bad RIP value.
RSP: 002b:00007fe323f45cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000078bf08 RCX: 000000000045c369
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000078bf08
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c
R13: 00007ffe350385df R14: 00007fe323f469c0 R15: 000000000078bf0c

The buggy address belongs to the page:
page:ffffea00019bc0c0 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x2
flags: 0xfffe0000000000()
raw: 00fffe0000000000 ffffea00019bcd48 ffffea00018941c8 0000000000000000
raw: 0000000000000002 0000000000000000 00000000ffffff7f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888066f03a00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888066f03a80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888066f03b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888066f03b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888066f03c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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