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WARNING: held lock freed! (2)

Status: fixed on 2019/08/27 17:15
Subsystems: hams
[Documentation on labels]
Reported-by: syzbot+e54ed2cb16c6da22c549@syzkaller.appspotmail.com
Fix commit: 4638faac0327 netrom: hold sock when setting skb->destructor
First crash: 1749d, last: 1749d
Cause bisection: introduced by (bisect log) :
commit c8c8218ec5af5d2598381883acbefbf604e56b5e
Author: Cong Wang <xiyou.wangcong@gmail.com>
Date: Thu Jun 27 21:30:58 2019 +0000

  netrom: fix a memory leak in nr_rx_frame()

Crash: WARNING: refcount bug in nr_insert_socket (log)
Repro: C syz .config
  
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
Reminder: 13 open syzbot bugs in "net/netrom" subsystem 2 (2) 2019/07/24 17:02
WARNING: held lock freed! (2) 0 (1) 2019/07/08 19:37
▶ ▼ Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING: held lock freed! sctp C 497 2281d 2292d 4/26 fixed on 2018/01/22 13:19

Sample crash report:
=========================
WARNING: held lock freed!
5.2.0-rc6+ #75 Not tainted
-------------------------
syz-executor315/8559 is freeing memory ffff88809faed2c0-ffff88809faedabf, with a lock still held there!
00000000cf45dbdb (sk_lock-AF_NETROM){+.+.}, at: lock_sock include/net/sock.h:1522 [inline]
00000000cf45dbdb (sk_lock-AF_NETROM){+.+.}, at: nr_release+0x11a/0x3b0 net/netrom/af_netrom.c:522
2 locks held by syz-executor315/8559:
 #0: 00000000c0a19dcd (&sb->s_type->i_mutex_key#11){+.+.}, at: inode_lock include/linux/fs.h:778 [inline]
 #0: 00000000c0a19dcd (&sb->s_type->i_mutex_key#11){+.+.}, at: __sock_release+0x89/0x2a0 net/socket.c:600
 #1: 00000000cf45dbdb (sk_lock-AF_NETROM){+.+.}, at: lock_sock include/net/sock.h:1522 [inline]
 #1: 00000000cf45dbdb (sk_lock-AF_NETROM){+.+.}, at: nr_release+0x11a/0x3b0 net/netrom/af_netrom.c:522

stack backtrace:
CPU: 0 PID: 8559 Comm: syz-executor315 Not tainted 5.2.0-rc6+ #75
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+0x172/0x1f0 lib/dump_stack.c:113
 print_freed_lock_bug kernel/locking/lockdep.c:5077 [inline]
 debug_check_no_locks_freed.cold+0x9d/0xa9 kernel/locking/lockdep.c:5110
 kfree+0xb1/0x220 mm/slab.c:3752
 sk_prot_free net/core/sock.c:1636 [inline]
 __sk_destruct+0x4f7/0x6e0 net/core/sock.c:1722
 sk_destruct+0x7b/0x90 net/core/sock.c:1730
 __sk_free+0xce/0x300 net/core/sock.c:1741
 sk_free+0x42/0x50 net/core/sock.c:1752
 sock_put include/net/sock.h:1725 [inline]
 nr_destroy_socket+0x3df/0x4a0 net/netrom/af_netrom.c:288
 nr_release+0x323/0x3b0 net/netrom/af_netrom.c:530
 __sock_release+0xce/0x2a0 net/socket.c:601
 sock_close+0x1b/0x30 net/socket.c:1273
 __fput+0x2ff/0x890 fs/file_table.c:280
 ____fput+0x16/0x20 fs/file_table.c:313
 task_work_run+0x145/0x1c0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:185 [inline]
 exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:168
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x58e/0x680 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x447269
Code: e8 7c 14 03 00 48 83 c4 18 c3 0f 1f 80 00 00 00 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 0f 83 cb 0e fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f653a7bed88 EFLAGS: 00000246 ORIG_RAX: 000000000000002d
RAX: ffffffffffffff95 RBX: 00000000006dcc48 RCX: 0000000000447269
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00000000006dcc40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc4c
R13: 0000003066736362 R14: 002cc7eb47000000 R15: 0000003066736362
==================================================================
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+0x28a/0x2e0 kernel/locking/spinlock_debug.c:112
Read of size 4 at addr ffff88809faed34c by task syz-executor315/8559

CPU: 1 PID: 8559 Comm: syz-executor315 Not tainted 5.2.0-rc6+ #75
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+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188
 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 kasan_report+0x12/0x20 mm/kasan/common.c:614
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/generic_report.c:131
 debug_spin_lock_before kernel/locking/spinlock_debug.c:83 [inline]
 do_raw_spin_lock+0x28a/0x2e0 kernel/locking/spinlock_debug.c:112
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:136 [inline]
 _raw_spin_lock_bh+0x3b/0x50 kernel/locking/spinlock.c:175
 spin_lock_bh include/linux/spinlock.h:343 [inline]
 release_sock+0x20/0x1c0 net/core/sock.c:2928
 nr_release+0x2df/0x3b0 net/netrom/af_netrom.c:553
 __sock_release+0xce/0x2a0 net/socket.c:601
 sock_close+0x1b/0x30 net/socket.c:1273
 __fput+0x2ff/0x890 fs/file_table.c:280
 ____fput+0x16/0x20 fs/file_table.c:313
 task_work_run+0x145/0x1c0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:185 [inline]
 exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:168
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x58e/0x680 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x447269
Code: e8 7c 14 03 00 48 83 c4 18 c3 0f 1f 80 00 00 00 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 0f 83 cb 0e fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f653a7bed88 EFLAGS: 00000246 ORIG_RAX: 000000000000002d
RAX: ffffffffffffff95 RBX: 00000000006dcc48 RCX: 0000000000447269
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00000000006dcc40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc4c
R13: 0000003066736362 R14: 002cc7eb47000000 R15: 0000003066736362

Allocated by task 8562:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_kmalloc mm/kasan/common.c:489 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503
 __do_kmalloc mm/slab.c:3660 [inline]
 __kmalloc+0x15c/0x740 mm/slab.c:3669
 kmalloc include/linux/slab.h:552 [inline]
 sk_prot_alloc+0x19c/0x2e0 net/core/sock.c:1599
 sk_alloc+0x39/0xf70 net/core/sock.c:1653
 nr_make_new net/netrom/af_netrom.c:476 [inline]
 nr_rx_frame+0x733/0x1e70 net/netrom/af_netrom.c:959
 nr_loopback_timer+0x7b/0x170 net/netrom/nr_loopback.c:59
 call_timer_fn+0x193/0x720 kernel/time/timer.c:1322
 expire_timers kernel/time/timer.c:1366 [inline]
 __run_timers kernel/time/timer.c:1685 [inline]
 __run_timers kernel/time/timer.c:1653 [inline]
 run_timer_softirq+0x66f/0x1740 kernel/time/timer.c:1698
 __do_softirq+0x25c/0x94c kernel/softirq.c:292

Freed by task 8559:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
 __cache_free mm/slab.c:3432 [inline]
 kfree+0xcf/0x220 mm/slab.c:3755
 sk_prot_free net/core/sock.c:1636 [inline]
 __sk_destruct+0x4f7/0x6e0 net/core/sock.c:1722
 sk_destruct+0x7b/0x90 net/core/sock.c:1730
 __sk_free+0xce/0x300 net/core/sock.c:1741
 sk_free+0x42/0x50 net/core/sock.c:1752
 sock_put include/net/sock.h:1725 [inline]
 nr_destroy_socket+0x3df/0x4a0 net/netrom/af_netrom.c:288
 nr_release+0x323/0x3b0 net/netrom/af_netrom.c:530
 __sock_release+0xce/0x2a0 net/socket.c:601
 sock_close+0x1b/0x30 net/socket.c:1273
 __fput+0x2ff/0x890 fs/file_table.c:280
 ____fput+0x16/0x20 fs/file_table.c:313
 task_work_run+0x145/0x1c0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:185 [inline]
 exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:168
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x58e/0x680 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88809faed2c0
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 140 bytes inside of
 2048-byte region [ffff88809faed2c0, ffff88809faedac0)
The buggy address belongs to the page:
page:ffffea00027ebb00 refcount:1 mapcount:0 mapping:ffff8880aa400c40 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea000242cd08 ffffea00023df908 ffff8880aa400c40
raw: 0000000000000000 ffff88809faec1c0 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809faed200: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88809faed280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff88809faed300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff88809faed380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809faed400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/07/05 03:59 net-old 9d1bc24b52fb 429efa16 .config console log report syz C ci-upstream-net-this-kasan-gce
* Struck through repros no longer work on HEAD.