syzbot

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BUG: KASAN: use-after-free in __lock_acquire+0x2c57/0x3f20 kernel/locking/lockdep.c:3369
Read of size 8 at addr ffff8880b4073b60 by task vhost-16043/16044

CPU: 0 PID: 16044 Comm: vhost-16043 Not tainted 4.14.277-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:430
 __lock_acquire+0x2c57/0x3f20 kernel/locking/lockdep.c:3369
 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:152
 spin_lock include/linux/spinlock.h:317 [inline]
 ptr_ring_consume_batched include/linux/ptr_ring.h:361 [inline]
 skb_array_consume_batched include/linux/skb_array.h:103 [inline]
 vhost_net_buf_produce drivers/vhost/net.c:167 [inline]
 vhost_net_buf_peek+0x1ee/0x640 drivers/vhost/net.c:190
 peek_head_len drivers/vhost/net.c:593 [inline]
 vhost_net_rx_peek_head_len drivers/vhost/net.c:623 [inline]
 handle_rx+0x377/0x1710 drivers/vhost/net.c:780
 vhost_worker+0x267/0x450 drivers/vhost/vhost.c:364
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 16043:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 __do_kmalloc mm/slab.c:3720 [inline]
 __kmalloc+0x15a/0x400 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 sk_prot_alloc+0x1ba/0x290 net/core/sock.c:1484
 sk_alloc+0x36/0xcd0 net/core/sock.c:1538
 tun_chr_open+0x7b/0x540 drivers/net/tun.c:2696
 misc_open+0x337/0x460 drivers/char/misc.c:154
 chrdev_open+0x23c/0x6d0 fs/char_dev.c:423
 do_dentry_open+0x44b/0xec0 fs/open.c:777
 vfs_open+0x105/0x220 fs/open.c:888
 do_last fs/namei.c:3428 [inline]
 path_openat+0x628/0x2970 fs/namei.c:3569
 do_filp_open+0x179/0x3c0 fs/namei.c:3603
 do_sys_open+0x296/0x410 fs/open.c:1081
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 16043:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 sk_prot_free net/core/sock.c:1521 [inline]
 __sk_destruct+0x5e3/0x760 net/core/sock.c:1600
 sk_destruct net/core/sock.c:1615 [inline]
 __sk_free+0xd9/0x2d0 net/core/sock.c:1623
 sk_free+0x2b/0x40 net/core/sock.c:1634
 sock_put include/net/sock.h:1664 [inline]
 __tun_detach+0x963/0xf60 drivers/net/tun.c:587
 tun_detach drivers/net/tun.c:594 [inline]
 tun_chr_close+0x41/0x60 drivers/net/tun.c:2732
 __fput+0x25f/0x7a0 fs/file_table.c:210
 task_work_run+0x11f/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff8880b4073580
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 1504 bytes inside of
 2048-byte region [ffff8880b4073580, ffff8880b4073d80)
The buggy address belongs to the page:
page:ffffea0002d01c80 count:1 mapcount:0 mapping:ffff8880b4072480 index:0xffff8880b4072d00 compound_mapcount: 0
flags: 0xfff00000008100(slab|head)
raw: 00fff00000008100 ffff8880b4072480 ffff8880b4072d00 0000000100000002
raw: ffffea00027a06a0 ffffea00028534a0 ffff88813fe74c40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880b4073a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880b4073a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880b4073b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff8880b4073b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880b4073c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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