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WARNING: held lock freed in pppol2tp_release (2)

Status: upstream: reported syz repro on 2020/02/27 22:29
Reported-by: syzbot+5643653524ee72807f34@syzkaller.appspotmail.com
First crash: 1730d, last: 1625d
Fix bisection the fix commit could be any of (bisect log):
  98db2bf27b9e Linux 4.14.171
  56dfe6252c68 Linux 4.14.188
   
▶ ▼ Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 WARNING: held lock freed in pppol2tp_release 3 1853d 1951d 0/1 auto-closed as invalid on 2020/02/25 03:46
▶ ▼ Last patch testing requests (2)
Created Duration User Patch Repo Result
2023/01/25 10:32 11m retest repro linux-4.14.y report log
2022/09/07 16:27 13m retest repro linux-4.14.y report log
▶ ▼ Fix bisection attempts (2)
Created Duration User Patch Repo Result
2020/07/12 11:40 31m bisect fix linux-4.14.y OK (2) job log
2020/06/12 11:07 25m bisect fix linux-4.14.y OK (0) job log log

Sample crash report:
IPv6: ADDRCONF(NETDEV_UP): batadv_slave_1: link is not ready
batman_adv: batadv0: Interface activated: batadv_slave_1
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
=========================
WARNING: held lock freed!
4.14.171-syzkaller #0 Not tainted
-------------------------
syz-executor.0/7416 is freeing memory ffff8880a98f62c0-ffff8880a98f6abf, with a lock still held there!
 (sk_lock-AF_PPPOX){+.+.}, at: [<ffffffff85c2af39>] lock_sock include/net/sock.h:1467 [inline]
 (sk_lock-AF_PPPOX){+.+.}, at: [<ffffffff85c2af39>] pppol2tp_release+0x49/0x2f0 net/l2tp/l2tp_ppp.c:476
2 locks held by syz-executor.0/7416:
 #0:  (&sb->s_type->i_mutex_key#11){+.+.}, at: [<ffffffff84f6ce16>] inode_lock include/linux/fs.h:718 [inline]
 #0:  (&sb->s_type->i_mutex_key#11){+.+.}, at: [<ffffffff84f6ce16>] __sock_release+0x86/0x2b0 net/socket.c:601
 #1:  (sk_lock-AF_PPPOX){+.+.}, at: [<ffffffff85c2af39>] lock_sock include/net/sock.h:1467 [inline]
 #1:  (sk_lock-AF_PPPOX){+.+.}, at: [<ffffffff85c2af39>] pppol2tp_release+0x49/0x2f0 net/l2tp/l2tp_ppp.c:476

stack backtrace:
CPU: 1 PID: 7416 Comm: syz-executor.0 Not tainted 4.14.171-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+0x13e/0x194 lib/dump_stack.c:58
 print_freed_lock_bug kernel/locking/lockdep.c:4459 [inline]
 debug_check_no_locks_freed.cold+0x9c/0xa8 kernel/locking/lockdep.c:4492
 kfree+0xae/0x260 mm/slab.c:3812
 sk_prot_free net/core/sock.c:1504 [inline]
 __sk_destruct+0x4f6/0x640 net/core/sock.c:1581
 sk_destruct+0x97/0xc0 net/core/sock.c:1596
 __sk_free+0x4c/0x220 net/core/sock.c:1604
 sk_free+0x2b/0x40 net/core/sock.c:1615
 sock_put include/net/sock.h:1658 [inline]
 pppol2tp_release+0x26a/0x2f0 net/l2tp/l2tp_ppp.c:493
 __sock_release+0xcd/0x2b0 net/socket.c:602
 sock_close+0x15/0x20 net/socket.c:1139
 __fput+0x25f/0x790 fs/file_table.c:210
 task_work_run+0x113/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1d6/0x220 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+0x42/0xb7
RIP: 0033:0x45c479
RSP: 002b:00007f9351ec1c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: 0000000000000000 RBX: 00007f9351ec26d4 RCX: 000000000045c479
RDX: 000000000000002e RSI: 0000000020000000 RDI: 0000000000000004
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000008d R14: 00000000004c2e4e R15: 000000000076bf2c
==================================================================
BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:183 [inline]
BUG: KASAN: use-after-free in debug_spin_lock_before kernel/locking/spinlock_debug.c:83 [inline]
BUG: KASAN: use-after-free in do_raw_spin_lock+0x1e4/0x230 kernel/locking/spinlock_debug.c:112
Read of size 4 at addr ffff8880a98f634c by task syz-executor.0/7416

CPU: 0 PID: 7416 Comm: syz-executor.0 Not tainted 4.14.171-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+0x13e/0x194 lib/dump_stack.c:58
 print_address_description.cold+0x7c/0x1e2 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2ae mm/kasan/report.c:393
 __read_once_size include/linux/compiler.h:183 [inline]
 debug_spin_lock_before kernel/locking/spinlock_debug.c:83 [inline]
 do_raw_spin_lock+0x1e4/0x230 kernel/locking/spinlock_debug.c:112
 spin_lock_bh include/linux/spinlock.h:322 [inline]
 release_sock+0x1b/0x1b0 net/core/sock.c:2777
 pppol2tp_release+0x219/0x2f0 net/l2tp/l2tp_ppp.c:495
 __sock_release+0xcd/0x2b0 net/socket.c:602
 sock_close+0x15/0x20 net/socket.c:1139
 __fput+0x25f/0x790 fs/file_table.c:210
 task_work_run+0x113/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1d6/0x220 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+0x42/0xb7
RIP: 0033:0x45c479
RSP: 002b:00007f9351ec1c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: 0000000000000000 RBX: 00007f9351ec26d4 RCX: 000000000045c479
RDX: 000000000000002e RSI: 0000000020000000 RDI: 0000000000000004
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000008d R14: 00000000004c2e4e R15: 000000000076bf2c

Allocated by task 7416:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:529
 __do_kmalloc mm/slab.c:3720 [inline]
 __kmalloc+0x15b/0x7c0 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 sk_prot_alloc+0x164/0x290 net/core/sock.c:1467
 sk_alloc+0x36/0xd60 net/core/sock.c:1521
 pppol2tp_create+0x2d/0x1e0 net/l2tp/l2tp_ppp.c:534
 pppox_create+0xf2/0x210 drivers/net/ppp/pppox.c:134
 __sock_create+0x2f2/0x620 net/socket.c:1275
 sock_create net/socket.c:1315 [inline]
 SYSC_socket net/socket.c:1345 [inline]
 SyS_socket+0xd2/0x170 net/socket.c:1325
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 7416:
 save_stack+0x32/0xa0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcb/0x260 mm/slab.c:3815
 sk_prot_free net/core/sock.c:1504 [inline]
 __sk_destruct+0x4f6/0x640 net/core/sock.c:1581
 sk_destruct+0x97/0xc0 net/core/sock.c:1596
 __sk_free+0x4c/0x220 net/core/sock.c:1604
 sk_free+0x2b/0x40 net/core/sock.c:1615
 sock_put include/net/sock.h:1658 [inline]
 pppol2tp_release+0x26a/0x2f0 net/l2tp/l2tp_ppp.c:493
 __sock_release+0xcd/0x2b0 net/socket.c:602
 sock_close+0x15/0x20 net/socket.c:1139
 __fput+0x25f/0x790 fs/file_table.c:210
 task_work_run+0x113/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1d6/0x220 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+0x42/0xb7

The buggy address belongs to the object at ffff8880a98f62c0
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 140 bytes inside of
 2048-byte region [ffff8880a98f62c0, ffff8880a98f6ac0)
The buggy address belongs to the page:
page:ffffea0002a63d80 count:1 mapcount:0 mapping:ffff8880a98f62c0 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffff8880a98f62c0 0000000000000000 0000000100000003
raw: ffffea000295b320 ffffea0001fb34a0 ffff88812fe56c40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a98f6200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a98f6280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff8880a98f6300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff8880a98f6380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a98f6400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/02/27 22:28 linux-4.14.y 98db2bf27b9e c88c7b75 .config console log report syz ci2-linux-4-14
2020/05/13 10:58 linux-4.14.y ab9dfda23248 9a6d42fb .config console log report ci2-linux-4-14
2020/04/28 07:15 linux-4.14.y 050272a0423e 0ce7569e .config console log report ci2-linux-4-14
2020/04/10 10:59 linux-4.14.y 4520f06b03ae a8c6a3f8 .config console log report ci2-linux-4-14
2020/03/26 23:16 linux-4.14.y 01364dad1d45 6d25c5a0 .config console log report ci2-linux-4-14
* Struck through repros no longer work on HEAD.