possible deadlock in perf_read

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syzbot

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Jul 25, 2019, 3:47:06 PM7/25/19
to syzkaller...@googlegroups.com
Hello,

syzbot found the following crash on:

HEAD commit: ff33472c Linux 4.14.134
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17d81f1fa00000
kernel config: https://syzkaller.appspot.com/x/.config?x=7918dc8aa910a9fb
dashboard link: https://syzkaller.appspot.com/bug?extid=93e350984a1eedc29917
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+93e350...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
4.14.134 #30 Not tainted
------------------------------------------------------
syz-executor.2/13189 is trying to acquire lock:
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
(&event->child_mutex){+.+.}, at: [<ffffffff816be1bb>] perf_read_group
kernel/events/core.c:4536 [inline]
(&event->child_mutex){+.+.}, at: [<ffffffff816be1bb>] __perf_read
kernel/events/core.c:4618 [inline]
(&event->child_mutex){+.+.}, at: [<ffffffff816be1bb>]
perf_read+0x2bb/0x810 kernel/events/core.c:4633
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'

but task is already holding lock:
(&cpuctx_mutex){+.+.}, at: [<ffffffff816bb8b0>]
perf_event_ctx_lock_nested+0x150/0x2c0 kernel/events/core.c:1235

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #5 (&cpuctx_mutex){+.+.}:
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3991
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
perf_event_init_cpu+0xc2/0x170 kernel/events/core.c:11223
perf_event_init+0x2d8/0x31a kernel/events/core.c:11270
start_kernel+0x3b6/0x6fd init/main.c:621
x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:381
x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:362
secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240

-> #4 (pmus_lock){+.+.}:
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3991
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
perf_event_init_cpu+0x2f/0x170 kernel/events/core.c:11217
cpuhp_invoke_callback+0x1ea/0x1ab0 kernel/cpu.c:184
cpuhp_up_callbacks kernel/cpu.c:572 [inline]
_cpu_up+0x228/0x530 kernel/cpu.c:1134
do_cpu_up+0x121/0x150 kernel/cpu.c:1169
cpu_up+0x1b/0x20 kernel/cpu.c:1177
smp_init+0x157/0x170 kernel/smp.c:578
kernel_init_freeable+0x30b/0x532 init/main.c:1067
kernel_init+0x12/0x162 init/main.c:999
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

-> #3 (cpu_hotplug_lock.rw_sem){++++}:
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3991
percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36
[inline]
percpu_down_read include/linux/percpu-rwsem.h:59 [inline]
cpus_read_lock+0x3d/0xc0 kernel/cpu.c:295
static_key_slow_inc+0x13/0x30 kernel/jump_label.c:123
tracepoint_add_func kernel/tracepoint.c:223 [inline]
tracepoint_probe_register_prio+0x4d6/0x6d0 kernel/tracepoint.c:283
tracepoint_probe_register+0x2b/0x40 kernel/tracepoint.c:304
trace_event_reg+0x277/0x330 kernel/trace/trace_events.c:305
perf_trace_event_reg kernel/trace/trace_event_perf.c:122 [inline]
perf_trace_event_init kernel/trace/trace_event_perf.c:197 [inline]
perf_trace_init+0x449/0xaa0 kernel/trace/trace_event_perf.c:221
perf_tp_event_init+0x7d/0xf0 kernel/events/core.c:8106
perf_try_init_event+0x164/0x200 kernel/events/core.c:9342
perf_init_event kernel/events/core.c:9380 [inline]
perf_event_alloc.part.0+0xd48/0x2530 kernel/events/core.c:9640
perf_event_alloc kernel/events/core.c:9993 [inline]
SYSC_perf_event_open+0xa2d/0x24b0 kernel/events/core.c:10097
SyS_perf_event_open+0x34/0x40 kernel/events/core.c:9983
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
kobject: 'loop3' (ffff8880a49ea960): kobject_uevent_env

-> #2 (tracepoints_mutex){+.+.}:
kobject: 'loop3' (ffff8880a49ea960): fill_kobj_path: path
= '/devices/virtual/block/loop3'
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3991
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
tracepoint_probe_register_prio+0x36/0x6d0 kernel/tracepoint.c:279
tracepoint_probe_register+0x2b/0x40 kernel/tracepoint.c:304
trace_event_reg+0x277/0x330 kernel/trace/trace_events.c:305
perf_trace_event_reg kernel/trace/trace_event_perf.c:122 [inline]
perf_trace_event_init kernel/trace/trace_event_perf.c:197 [inline]
perf_trace_init+0x449/0xaa0 kernel/trace/trace_event_perf.c:221
perf_tp_event_init+0x7d/0xf0 kernel/events/core.c:8106
perf_try_init_event+0x164/0x200 kernel/events/core.c:9342
perf_init_event kernel/events/core.c:9380 [inline]
perf_event_alloc.part.0+0xd48/0x2530 kernel/events/core.c:9640
perf_event_alloc kernel/events/core.c:9993 [inline]
SYSC_perf_event_open+0xa2d/0x24b0 kernel/events/core.c:10097
SyS_perf_event_open+0x34/0x40 kernel/events/core.c:9983
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7

-> #1 (event_mutex){+.+.}:
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3991
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234
tp_perf_event_destroy+0x16/0x20 kernel/events/core.c:8090
_free_event+0x330/0xe70 kernel/events/core.c:4238
free_event+0x38/0x50 kernel/events/core.c:4265
perf_event_release_kernel+0x364/0x7a0 kernel/events/core.c:4409
perf_release+0x37/0x50 kernel/events/core.c:4435
__fput+0x275/0x7a0 fs/file_table.c:210
____fput+0x16/0x20 fs/file_table.c:244
task_work_run+0x114/0x190 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x7df/0x2c10 kernel/exit.c:874
do_group_exit+0x111/0x330 kernel/exit.c:977
SYSC_exit_group kernel/exit.c:988 [inline]
SyS_exit_group+0x1d/0x20 kernel/exit.c:986
kobject: 'loop3' (ffff8880a49ea960): kobject_uevent_env
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7

-> #0 (&event->child_mutex){+.+.}:
kobject: 'loop3' (ffff8880a49ea960): fill_kobj_path: path
= '/devices/virtual/block/loop3'
check_prev_add kernel/locking/lockdep.c:1901 [inline]
check_prevs_add kernel/locking/lockdep.c:2018 [inline]
validate_chain kernel/locking/lockdep.c:2460 [inline]
__lock_acquire+0x2c89/0x45e0 kernel/locking/lockdep.c:3487
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3991
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
perf_read_group kernel/events/core.c:4536 [inline]
__perf_read kernel/events/core.c:4618 [inline]
perf_read+0x2bb/0x810 kernel/events/core.c:4633
do_loop_readv_writev fs/read_write.c:695 [inline]
do_loop_readv_writev fs/read_write.c:682 [inline]
do_iter_read+0x3e2/0x5b0 fs/read_write.c:919
vfs_readv+0xd3/0x130 fs/read_write.c:981
do_readv+0x10a/0x2d0 fs/read_write.c:1014
SYSC_readv fs/read_write.c:1101 [inline]
SyS_readv+0x28/0x30 fs/read_write.c:1098
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7

other info that might help us debug this:

Chain exists of:
&event->child_mutex --> pmus_lock --> &cpuctx_mutex

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&cpuctx_mutex);
lock(pmus_lock);
lock(&cpuctx_mutex);
lock(&event->child_mutex);

*** DEADLOCK ***

1 lock held by syz-executor.2/13189:
#0: (&cpuctx_mutex){+.+.}, at: [<ffffffff816bb8b0>]
perf_event_ctx_lock_nested+0x150/0x2c0 kernel/events/core.c:1235

stack backtrace:
CPU: 1 PID: 13189 Comm: syz-executor.2 Not tainted 4.14.134 #30
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+0x138/0x19c lib/dump_stack.c:53
print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1258
check_prev_add kernel/locking/lockdep.c:1901 [inline]
check_prevs_add kernel/locking/lockdep.c:2018 [inline]
validate_chain kernel/locking/lockdep.c:2460 [inline]
__lock_acquire+0x2c89/0x45e0 kernel/locking/lockdep.c:3487
kobject: 'loop3' (ffff8880a49ea960): kobject_uevent_env
kobject: 'loop3' (ffff8880a49ea960): fill_kobj_path: path
= '/devices/virtual/block/loop3'
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3991
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
perf_read_group kernel/events/core.c:4536 [inline]
__perf_read kernel/events/core.c:4618 [inline]
perf_read+0x2bb/0x810 kernel/events/core.c:4633
do_loop_readv_writev fs/read_write.c:695 [inline]
do_loop_readv_writev fs/read_write.c:682 [inline]
do_iter_read+0x3e2/0x5b0 fs/read_write.c:919
vfs_readv+0xd3/0x130 fs/read_write.c:981
do_readv+0x10a/0x2d0 fs/read_write.c:1014
SYSC_readv fs/read_write.c:1101 [inline]
SyS_readv+0x28/0x30 fs/read_write.c:1098
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459829
RSP: 002b:00007f852375bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000013
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459829
RDX: 0000000000000001 RSI: 00000000200002c0 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f852375c6d4
R13: 00000000004c69e4 R14: 00000000004dbc50 R15: 00000000ffffffff
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
audit: type=1400 audit(1564080389.951:108): avc: denied { getopt } for
pid=13225 comm="syz-executor.5"
scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tclass=netlink_generic_socket permissive=1
audit: type=1400 audit(1564080389.961:109): avc: denied { ioctl } for
pid=13225 comm="syz-executor.5" path="socket:[46218]" dev="sockfs"
ino=46218 ioctlcmd=0x6613
scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tclass=netlink_generic_socket permissive=1
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop3' (ffff8880a49ea960): kobject_uevent_env
kobject: 'loop3' (ffff8880a49ea960): fill_kobj_path: path
= '/devices/virtual/block/loop3'
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop3' (ffff8880a49ea960): kobject_uevent_env
kobject: 'loop3' (ffff8880a49ea960): fill_kobj_path: path
= '/devices/virtual/block/loop3'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
net_ratelimit: 22 callbacks suppressed
protocol 88fb is buggy, dev hsr_slave_0
protocol 88fb is buggy, dev hsr_slave_0
protocol 88fb is buggy, dev hsr_slave_1
protocol 88fb is buggy, dev hsr_slave_1
protocol 88fb is buggy, dev hsr_slave_0
protocol 88fb is buggy, dev hsr_slave_1
protocol 88fb is buggy, dev hsr_slave_0
protocol 88fb is buggy, dev hsr_slave_1
protocol 88fb is buggy, dev hsr_slave_0
protocol 88fb is buggy, dev hsr_slave_1
kobject: 'loop3' (ffff8880a49ea960): kobject_uevent_env
kobject: 'loop3' (ffff8880a49ea960): fill_kobj_path: path
= '/devices/virtual/block/loop3'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
IPVS: length: 199 != 8
IPVS: length: 199 != 8
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop3' (ffff8880a49ea960): kobject_uevent_env
kobject: 'loop3' (ffff8880a49ea960): fill_kobj_path: path
= '/devices/virtual/block/loop3'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop3' (ffff8880a49ea960): kobject_uevent_env
kobject: 'loop3' (ffff8880a49ea960): fill_kobj_path: path
= '/devices/virtual/block/loop3'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop3' (ffff8880a49ea960): kobject_uevent_env
kobject: 'loop3' (ffff8880a49ea960): fill_kobj_path: path
= '/devices/virtual/block/loop3'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop3' (ffff8880a49ea960): kobject_uevent_env
kobject: 'loop3' (ffff8880a49ea960): fill_kobj_path: path
= '/devices/virtual/block/loop3'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop3' (ffff8880a49ea960): kobject_uevent_env
kobject: 'loop3' (ffff8880a49ea960): fill_kobj_path: path
= '/devices/virtual/block/loop3'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop3' (ffff8880a49ea960): kobject_uevent_env
kobject: 'loop3' (ffff8880a49ea960): fill_kobj_path: path
= '/devices/virtual/block/loop3'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop3' (ffff8880a49ea960): kobject_uevent_env
kobject: 'loop3' (ffff8880a49ea960): fill_kobj_path: path
= '/devices/virtual/block/loop3'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
net_ratelimit: 18 callbacks suppressed
protocol 88fb is buggy, dev hsr_slave_0
protocol 88fb is buggy, dev hsr_slave_1
protocol 88fb is buggy, dev hsr_slave_0
protocol 88fb is buggy, dev hsr_slave_1
protocol 88fb is buggy, dev hsr_slave_0
protocol 88fb is buggy, dev hsr_slave_1
protocol 88fb is buggy, dev hsr_slave_0
protocol 88fb is buggy, dev hsr_slave_1
protocol 88fb is buggy, dev hsr_slave_0
protocol 88fb is buggy, dev hsr_slave_1
kobject: 'loop0' (ffff88805c152e20): kobject_uevent_env
kobject: 'loop0' (ffff88805c152e20): fill_kobj_path: path
= '/devices/virtual/block/loop0'
kobject: 'loop3' (ffff8880a49ea960): kobject_uevent_env
kobject: 'loop3' (ffff8880a49ea960): fill_kobj_path: path
= '/devices/virtual/block/loop3'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
kobject: 'loop4' (ffff8880a4a4a9e0): kobject_uevent_env
kobject: 'loop4' (ffff8880a4a4a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

syzbot

unread,
Oct 17, 2019, 12:18:07 PM10/17/19
to syzkaller...@googlegroups.com
syzbot has found a reproducer for the following crash on:

HEAD commit: e132c8d7 Linux 4.14.149
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1258f2cf600000
kernel config: https://syzkaller.appspot.com/x/.config?x=be18b5a03bbccd
dashboard link: https://syzkaller.appspot.com/bug?extid=93e350984a1eedc29917
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=150b5abb600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1531cf6f600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+93e350...@syzkaller.appspotmail.com

audit: type=1400 audit(1571328833.418:36): avc: denied { map } for
pid=6901 comm="syz-executor049" path="/root/syz-executor049681636"
dev="sda1" ino=16483 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
IPVS: ftp: loaded support on port[0] = 21
======================================================
WARNING: possible circular locking dependency detected
4.14.149 #0 Not tainted
------------------------------------------------------
syz-executor049/6905 is trying to acquire lock:
(&event->child_mutex){+.+.}, at: [<ffffffff816bfac0>] perf_read_group
kernel/events/core.c:4536 [inline]
(&event->child_mutex){+.+.}, at: [<ffffffff816bfac0>] __perf_read
kernel/events/core.c:4618 [inline]
(&event->child_mutex){+.+.}, at: [<ffffffff816bfac0>]
perf_read+0x2c0/0x820 kernel/events/core.c:4633

but task is already holding lock:
(&cpuctx_mutex){+.+.}, at: [<ffffffff816bd1b0>]
perf_event_ctx_lock_nested+0x150/0x2c0 kernel/events/core.c:1235

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #5 (&cpuctx_mutex){+.+.}:
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
perf_event_init_cpu+0xc2/0x170 kernel/events/core.c:11223
perf_event_init+0x2d8/0x31a kernel/events/core.c:11270
start_kernel+0x3b6/0x6fd init/main.c:621
x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:381
x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:362
secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:240

-> #4 (pmus_lock){+.+.}:
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
perf_event_init_cpu+0x2f/0x170 kernel/events/core.c:11217
cpuhp_invoke_callback+0x1ea/0x1ab0 kernel/cpu.c:184
cpuhp_up_callbacks kernel/cpu.c:572 [inline]
_cpu_up+0x228/0x530 kernel/cpu.c:1134
do_cpu_up+0x121/0x150 kernel/cpu.c:1169
cpu_up+0x1b/0x20 kernel/cpu.c:1177
smp_init+0x157/0x170 kernel/smp.c:578
kernel_init_freeable+0x30b/0x532 init/main.c:1067
kernel_init+0x12/0x162 init/main.c:999
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

-> #3 (cpu_hotplug_lock.rw_sem){++++}:
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994
percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36
[inline]
percpu_down_read include/linux/percpu-rwsem.h:59 [inline]
cpus_read_lock+0x3d/0xc0 kernel/cpu.c:295
static_key_slow_inc+0x13/0x30 kernel/jump_label.c:123
tracepoint_add_func kernel/tracepoint.c:223 [inline]
tracepoint_probe_register_prio+0x4d6/0x6d0 kernel/tracepoint.c:283
tracepoint_probe_register+0x2b/0x40 kernel/tracepoint.c:304
trace_event_reg+0x277/0x330 kernel/trace/trace_events.c:305
perf_trace_event_reg kernel/trace/trace_event_perf.c:122 [inline]
perf_trace_event_init kernel/trace/trace_event_perf.c:197 [inline]
perf_trace_init+0x449/0xaa0 kernel/trace/trace_event_perf.c:221
perf_tp_event_init+0x7d/0xf0 kernel/events/core.c:8106
perf_try_init_event+0x164/0x200 kernel/events/core.c:9342
perf_init_event kernel/events/core.c:9380 [inline]
perf_event_alloc.part.0+0xd90/0x25b0 kernel/events/core.c:9640
perf_event_alloc kernel/events/core.c:9993 [inline]
SYSC_perf_event_open+0xad1/0x2690 kernel/events/core.c:10097
SyS_perf_event_open+0x34/0x40 kernel/events/core.c:9983
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7

-> #2 (tracepoints_mutex){+.+.}:
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
tracepoint_probe_register_prio+0x36/0x6d0 kernel/tracepoint.c:279
tracepoint_probe_register+0x2b/0x40 kernel/tracepoint.c:304
trace_event_reg+0x277/0x330 kernel/trace/trace_events.c:305
perf_trace_event_reg kernel/trace/trace_event_perf.c:122 [inline]
perf_trace_event_init kernel/trace/trace_event_perf.c:197 [inline]
perf_trace_init+0x449/0xaa0 kernel/trace/trace_event_perf.c:221
perf_tp_event_init+0x7d/0xf0 kernel/events/core.c:8106
perf_try_init_event+0x164/0x200 kernel/events/core.c:9342
perf_init_event kernel/events/core.c:9380 [inline]
perf_event_alloc.part.0+0xd90/0x25b0 kernel/events/core.c:9640
perf_event_alloc kernel/events/core.c:9993 [inline]
SYSC_perf_event_open+0xad1/0x2690 kernel/events/core.c:10097
SyS_perf_event_open+0x34/0x40 kernel/events/core.c:9983
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7

-> #1 (event_mutex){+.+.}:
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
perf_trace_destroy+0x28/0x100 kernel/trace/trace_event_perf.c:234
tp_perf_event_destroy+0x16/0x20 kernel/events/core.c:8090
_free_event+0x330/0xe70 kernel/events/core.c:4238
free_event+0x38/0x50 kernel/events/core.c:4265
perf_event_release_kernel+0x364/0x880 kernel/events/core.c:4409
perf_release+0x37/0x50 kernel/events/core.c:4435
__fput+0x275/0x7a0 fs/file_table.c:210
____fput+0x16/0x20 fs/file_table.c:244
task_work_run+0x114/0x190 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:191 [inline]
exit_to_usermode_loop+0x1da/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+0x4bc/0x640 arch/x86/entry/common.c:297
entry_SYSCALL_64_after_hwframe+0x42/0xb7

-> #0 (&event->child_mutex){+.+.}:
check_prev_add kernel/locking/lockdep.c:1901 [inline]
check_prevs_add kernel/locking/lockdep.c:2018 [inline]
validate_chain kernel/locking/lockdep.c:2460 [inline]
__lock_acquire+0x2cb3/0x4620 kernel/locking/lockdep.c:3487
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
perf_read_group kernel/events/core.c:4536 [inline]
__perf_read kernel/events/core.c:4618 [inline]
perf_read+0x2c0/0x820 kernel/events/core.c:4633
do_loop_readv_writev fs/read_write.c:695 [inline]
do_loop_readv_writev fs/read_write.c:682 [inline]
do_iter_read+0x3e2/0x5b0 fs/read_write.c:919
vfs_readv+0xd3/0x130 fs/read_write.c:981
do_readv+0x10a/0x2d0 fs/read_write.c:1014
SYSC_readv fs/read_write.c:1101 [inline]
SyS_readv+0x28/0x30 fs/read_write.c:1098
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7

other info that might help us debug this:

Chain exists of:
&event->child_mutex --> pmus_lock --> &cpuctx_mutex

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&cpuctx_mutex);
lock(pmus_lock);
lock(&cpuctx_mutex);
lock(&event->child_mutex);

*** DEADLOCK ***

1 lock held by syz-executor049/6905:
#0: (&cpuctx_mutex){+.+.}, at: [<ffffffff816bd1b0>]
perf_event_ctx_lock_nested+0x150/0x2c0 kernel/events/core.c:1235

stack backtrace:
CPU: 1 PID: 6905 Comm: syz-executor049 Not tainted 4.14.149 #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+0x138/0x197 lib/dump_stack.c:53
print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1258
check_prev_add kernel/locking/lockdep.c:1901 [inline]
check_prevs_add kernel/locking/lockdep.c:2018 [inline]
validate_chain kernel/locking/lockdep.c:2460 [inline]
__lock_acquire+0x2cb3/0x4620 kernel/locking/lockdep.c:3487
lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3994
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
perf_read_group kernel/events/core.c:4536 [inline]
__perf_read kernel/events/core.c:4618 [inline]
perf_read+0x2c0/0x820 kernel/events/core.c:4633
do_loop_readv_writev fs/read_write.c:695 [inline]
do_loop_readv_writev fs/read_write.c:682 [inline]
do_iter_read+0x3e2/0x5b0 fs/read_write.c:919
vfs_readv+0xd3/0x130 fs/read_write.c:981
do_readv+0x10a/0x2d0 fs/read_write.c:1014
SYSC_readv fs/read_write.c:1101 [inline]
SyS_readv+0x28/0x30 fs/read_write.c:1098
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x443549
RSP: 002b:00007fff8cdec9a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000013
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000443549
RDX: 0000000000000001 RSI: 0000000020000200 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000404350 R14: 0000000000000000 R15: 0000000000000000

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