syzbot


possible deadlock in perf_event_detach_bpf_prog

Status: fixed on 2018/05/08 18:30
Subsystems: bpf trace
[Documentation on labels]
Reported-by: syzbot+dc5ca0e4c9bfafaf2bae@syzkaller.appspotmail.com
Fix commit: 3a38bb98d9ab bpf/tracing: fix a deadlock in perf_event_detach_bpf_prog
First crash: 2248d, last: 2248d
Discussions (6)
Title Replies (including bot) Last reply
[PATCH 4.16 00/72] 4.16.9-stable review 86 (86) 2018/05/15 06:47
[PATCH bpf v4] bpf/tracing: fix a deadlock in perf_event_detach_bpf_prog 2 (2) 2018/04/10 23:14
[PATCH bpf v3] bpf/tracing: fix a deadlock in perf_event_detach_bpf_prog 3 (3) 2018/04/10 16:04
[PATCH bpf v2] bpf/tracing: fix a deadlock in perf_event_detach_bpf_prog 1 (1) 2018/04/10 07:13
[PATCH bpf] bpf/tracing: fix a deadlock in perf_event_detach_bpf_prog 4 (4) 2018/04/10 00:51
possible deadlock in perf_event_detach_bpf_prog 2 (3) 2018/04/08 15:56

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
4.16.0-rc7+ #3 Not tainted
------------------------------------------------------
syz-executor7/24531 is trying to acquire lock:
 (bpf_event_mutex){+.+.}, at: [<000000008a849b07>] perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854

but task is already holding lock:
 (&mm->mmap_sem){++++}, at: [<0000000038768f87>] vm_mmap_pgoff+0x198/0x280 mm/util.c:353

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&mm->mmap_sem){++++}:
       __might_fault+0x13a/0x1d0 mm/memory.c:4571
       _copy_to_user+0x2c/0xc0 lib/usercopy.c:25
       copy_to_user include/linux/uaccess.h:155 [inline]
       bpf_prog_array_copy_info+0xf2/0x1c0 kernel/bpf/core.c:1694
       perf_event_query_prog_array+0x1c7/0x2c0 kernel/trace/bpf_trace.c:891
       _perf_ioctl kernel/events/core.c:4750 [inline]
       perf_ioctl+0x3e1/0x1480 kernel/events/core.c:4770
       vfs_ioctl fs/ioctl.c:46 [inline]
       do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
       SYSC_ioctl fs/ioctl.c:701 [inline]
       SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
       do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
       entry_SYSCALL_64_after_hwframe+0x42/0xb7

-> #0 (bpf_event_mutex){+.+.}:
       lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893
       mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
       perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854
       perf_event_free_bpf_prog kernel/events/core.c:8147 [inline]
       _free_event+0xbdb/0x10f0 kernel/events/core.c:4116
       put_event+0x24/0x30 kernel/events/core.c:4204
       perf_mmap_close+0x60d/0x1010 kernel/events/core.c:5172
       remove_vma+0xb4/0x1b0 mm/mmap.c:172
       remove_vma_list mm/mmap.c:2490 [inline]
       do_munmap+0x82a/0xdf0 mm/mmap.c:2731
       mmap_region+0x59e/0x15a0 mm/mmap.c:1646
       do_mmap+0x6c0/0xe00 mm/mmap.c:1483
       do_mmap_pgoff include/linux/mm.h:2223 [inline]
       vm_mmap_pgoff+0x1de/0x280 mm/util.c:355
       SYSC_mmap_pgoff mm/mmap.c:1533 [inline]
       SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1491
       SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
       SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91
       do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
       entry_SYSCALL_64_after_hwframe+0x42/0xb7

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&mm->mmap_sem);
                               lock(bpf_event_mutex);
                               lock(&mm->mmap_sem);
  lock(bpf_event_mutex);

 *** DEADLOCK ***

1 lock held by syz-executor7/24531:
 #0:  (&mm->mmap_sem){++++}, at: [<0000000038768f87>] vm_mmap_pgoff+0x198/0x280 mm/util.c:353

stack backtrace:
CPU: 0 PID: 24531 Comm: syz-executor7 Not tainted 4.16.0-rc7+ #3
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+0x194/0x24d lib/dump_stack.c:53
 print_circular_bug.isra.38+0x2cd/0x2dc kernel/locking/lockdep.c:1223
 check_prev_add kernel/locking/lockdep.c:1863 [inline]
 check_prevs_add kernel/locking/lockdep.c:1976 [inline]
 validate_chain kernel/locking/lockdep.c:2417 [inline]
 __lock_acquire+0x30a8/0x3e00 kernel/locking/lockdep.c:3431
 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
 __mutex_lock_common kernel/locking/mutex.c:756 [inline]
 __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
 perf_event_detach_bpf_prog+0x92/0x3d0 kernel/trace/bpf_trace.c:854
 perf_event_free_bpf_prog kernel/events/core.c:8147 [inline]
 _free_event+0xbdb/0x10f0 kernel/events/core.c:4116
 put_event+0x24/0x30 kernel/events/core.c:4204
 perf_mmap_close+0x60d/0x1010 kernel/events/core.c:5172
 remove_vma+0xb4/0x1b0 mm/mmap.c:172
 remove_vma_list mm/mmap.c:2490 [inline]
 do_munmap+0x82a/0xdf0 mm/mmap.c:2731
 mmap_region+0x59e/0x15a0 mm/mmap.c:1646
 do_mmap+0x6c0/0xe00 mm/mmap.c:1483
 do_mmap_pgoff include/linux/mm.h:2223 [inline]
 vm_mmap_pgoff+0x1de/0x280 mm/util.c:355
 SYSC_mmap_pgoff mm/mmap.c:1533 [inline]
 SyS_mmap_pgoff+0x462/0x5f0 mm/mmap.c:1491
 SYSC_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
 SyS_mmap+0x16/0x20 arch/x86/kernel/sys_x86_64.c:91
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x454889
RSP: 002b:00007f5f44fdac68 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f5f44fdb6d4 RCX: 0000000000454889
RDX: 0000000000000000 RSI: 0000000000002000 RDI: 0000000020f1f000
RBP: 000000000072c010 R08: 0000000000000014 R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000003f4 R14: 00000000006f7f80 R15: 0000000000000002
bond0 (unregistering): Released all slaves
IPVS: ftp: loaded support on port[0] = 21
IPv6: ADDRCONF(NETDEV_UP): bridge0: link is not ready
IPv6: ADDRCONF(NETDEV_UP): bond0: link is not ready
8021q: adding VLAN 0 to HW filter on device bond0
IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
kernel msg: ebtables bug: please report to author: Wrong len argument
kernel msg: ebtables bug: please report to author: Wrong len argument
kernel msg: ebtables bug: please report to author: Wrong len argument
kernel msg: ebtables bug: please report to author: Wrong len argument
kernel msg: ebtables bug: please report to author: Wrong len argument
kernel msg: ebtables bug: please report to author: Wrong len argument
kernel msg: ebtables bug: please report to author: Wrong len argument

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/03/29 00:14 upstream 3eb2ce825ea1 bf5e585c .config console log report ci-upstream-kasan-gce-root
* Struck through repros no longer work on HEAD.