On Tue, Apr 6, 2021 at 6:01 AM syzbot <syzbot+7b6548ae483d6f4c64ae@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > ================================================================== > BUG: KASAN: use-after-free in __lock_acquire+0x3e6f/0x54c0 kernel/locking/lockdep.c:4770 > Read of size 8 at addr ffff888024f66238 by task syz-executor.1/14202 > > CPU: 0 PID: 14202 Comm: syz-executor.1 Not tainted 5.12.0-rc4-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:79 [inline] > dump_stack+0x141/0x1d7 lib/dump_stack.c:120 > print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232 > __kasan_report mm/kasan/report.c:399 [inline] > kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416 > __lock_acquire+0x3e6f/0x54c0 kernel/locking/lockdep.c:4770 > lock_acquire kernel/locking/lockdep.c:5510 [inline] > lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5475 > __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] > _raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:175 > spin_lock_bh include/linux/spinlock.h:359 [inline] > sk_psock_stop+0x2f/0x4d0 net/core/skmsg.c:750 > sock_map_close+0x172/0x390 net/core/sock_map.c:1534 > inet_release+0x12e/0x280 net/ipv4/af_inet.c:431 > __sock_release+0xcd/0x280 net/socket.c:599 > sock_close+0x18/0x20 net/socket.c:1258 > __fput+0x288/0x920 fs/file_table.c:280 > task_work_run+0xdd/0x1a0 kernel/task_work.c:140 > tracehook_notify_resume include/linux/tracehook.h:189 [inline] > exit_to_user_mode_loop kernel/entry/common.c:174 [inline] > exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:208 > __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline] > syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301 > entry_SYSCALL_64_after_hwframe+0x44/0xae > RIP: 0033:0x466459 > 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 bc ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007f1bde3a3188 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 > RAX: 0000000000000000 RBX: 000000000056bf60 RCX: 0000000000466459 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 > RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60 > R13: 00007ffe6eb13bbf R14: 00007f1bde3a3300 R15: 0000000000022000 [...] > Second to last potentially related work creation: > kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 > kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:345 > __call_rcu kernel/rcu/tree.c:3039 [inline] > call_rcu+0xb1/0x740 kernel/rcu/tree.c:3114 > queue_rcu_work+0x82/0xa0 kernel/workqueue.c:1753 > sk_psock_put include/linux/skmsg.h:446 [inline] > sock_map_unref+0x109/0x190 net/core/sock_map.c:182 > sock_hash_delete_from_link net/core/sock_map.c:918 [inline] > sock_map_unlink net/core/sock_map.c:1480 [inline] > sock_map_remove_links+0x389/0x530 net/core/sock_map.c:1492 > sock_map_close+0x12f/0x390 net/core/sock_map.c:1532 Looks like the last refcnt can be gone before sk_psock_stop(). Technically, we can call sk_psock_stop() before sock_map_remove_links(), the only barrier is the RCU read lock there. Let me see if we can get rid of that RCU read lock. Thanks.
