linux-stable.git/kernel, branch v5.4.11

tracing: Do not create directories if lockdown is in affect

2020-01-12T11:21:45+00:00

commit a356646a56857c2e5ad875beec734d7145ecd49a upstream.

If lockdown is disabling tracing on boot up, it prevents the tracing files
from even bering created. But when that happens, there's several places that
will give a warning that the files were not created as that is usually a
sign of a bug.

Add in strategic locations where a check is made to see if tracing is
disabled by lockdown, and if it is, do not go further, and fail silently
(but print that tracing is disabled by lockdown, without doing a WARN_ON()).

Cc: Matthew Garrett 
Fixes: 17911ff38aa5 ("tracing: Add locked_down checks to the open calls of files created for tracefs")
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

psi: Fix a division error in psi poll()

2020-01-12T11:21:36+00:00

[ Upstream commit c3466952ca1514158d7c16c9cfc48c27d5c5dc0f ]

The psi window size is a u64 an can be up to 10 seconds right now,
which exceeds the lower 32 bits of the variable. We currently use
div_u64 for it, which is meant only for 32-bit divisors. The result is
garbage pressure sampling values and even potential div0 crashes.

Use div64_u64.

Signed-off-by: Johannes Weiner 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Suren Baghdasaryan 
Cc: Jingfeng Xie 
Link: https://lkml.kernel.org/r/20191203183524.41378-3-hannes@cmpxchg.org
Signed-off-by: Sasha Levin

sched/psi: Fix sampling error and rare div0 crashes with cgroups and high uptime

2020-01-12T11:21:36+00:00

[ Upstream commit 3dfbe25c27eab7c90c8a7e97b4c354a9d24dd985 ]

Jingfeng reports rare div0 crashes in psi on systems with some uptime:

[58914.066423] divide error: 0000 [#1] SMP
[58914.070416] Modules linked in: ipmi_poweroff ipmi_watchdog toa overlay fuse tcp_diag inet_diag binfmt_misc aisqos(O) aisqos_hotfixes(O)
[58914.083158] CPU: 94 PID: 140364 Comm: kworker/94:2 Tainted: G W OE K 4.9.151-015.ali3000.alios7.x86_64 #1
[58914.093722] Hardware name: Alibaba Alibaba Cloud ECS/Alibaba Cloud ECS, BIOS 3.23.34 02/14/2019
[58914.102728] Workqueue: events psi_update_work
[58914.107258] task: ffff8879da83c280 task.stack: ffffc90059dcc000
[58914.113336] RIP: 0010:[] [] psi_update_stats+0x1c1/0x330
[58914.122183] RSP: 0018:ffffc90059dcfd60 EFLAGS: 00010246
[58914.127650] RAX: 0000000000000000 RBX: ffff8858fe98be50 RCX: 000000007744d640
[58914.134947] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00003594f700648e
[58914.142243] RBP: ffffc90059dcfdf8 R08: 0000359500000000 R09: 0000000000000000
[58914.149538] R10: 0000000000000000 R11: 0000000000000000 R12: 0000359500000000
[58914.156837] R13: 0000000000000000 R14: 0000000000000000 R15: ffff8858fe98bd78
[58914.164136] FS: 0000000000000000(0000) GS:ffff887f7f380000(0000) knlGS:0000000000000000
[58914.172529] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[58914.178467] CR2: 00007f2240452090 CR3: 0000005d5d258000 CR4: 00000000007606f0
[58914.185765] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[58914.193061] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[58914.200360] PKRU: 55555554
[58914.203221] Stack:
[58914.205383] ffff8858fe98bd48 00000000000002f0 0000002e81036d09 ffffc90059dcfde8
[58914.213168] ffff8858fe98bec8 0000000000000000 0000000000000000 0000000000000000
[58914.220951] 0000000000000000 0000000000000000 0000000000000000 0000000000000000
[58914.228734] Call Trace:
[58914.231337] [] psi_update_work+0x22/0x60
[58914.237067] [] process_one_work+0x189/0x420
[58914.243063] [] worker_thread+0x4e/0x4b0
[58914.248701] [] ? process_one_work+0x420/0x420
[58914.254869] [] kthread+0xe6/0x100
[58914.259994] [] ? kthread_park+0x60/0x60
[58914.265640] [] ret_from_fork+0x39/0x50
[58914.271193] Code: 41 29 c3 4d 39 dc 4d 0f 42 dc <49> f7 f1 48 8b 13 48 89 c7 48 c1
[58914.279691] RIP [] psi_update_stats+0x1c1/0x330

The crashing instruction is trying to divide the observed stall time
by the sampling period. The period, stored in R8, is not 0, but we are
dividing by the lower 32 bits only, which are all 0 in this instance.

We could switch to a 64-bit division, but the period shouldn't be that
big in the first place. It's the time between the last update and the
next scheduled one, and so should always be around 2s and comfortably
fit into 32 bits.

The bug is in the initialization of new cgroups: we schedule the first
sampling event in a cgroup as an offset of sched_clock(), but fail to
initialize the last_update timestamp, and it defaults to 0. That
results in a bogusly large sampling period the first time we run the
sampling code, and consequently we underreport pressure for the first
2s of a cgroup's life. But worse, if sched_clock() is sufficiently
advanced on the system, and the user gets unlucky, the period's lower
32 bits can all be 0 and the sampling division will crash.

Fix this by initializing the last update timestamp to the creation
time of the cgroup, thus correctly marking the start of the first
pressure sampling period in a new cgroup.

Reported-by: Jingfeng Xie 
Signed-off-by: Johannes Weiner 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Suren Baghdasaryan 
Link: https://lkml.kernel.org/r/20191203183524.41378-2-hannes@cmpxchg.org
Signed-off-by: Sasha Levin

locking/spinlock/debug: Fix various data races

2020-01-12T11:21:13+00:00

[ Upstream commit 1a365e822372ba24c9da0822bc583894f6f3d821 ]

This fixes various data races in spinlock_debug. By testing with KCSAN,
it is observable that the console gets spammed with data races reports,
suggesting these are extremely frequent.

Example data race report:

  read to 0xffff8ab24f403c48 of 4 bytes by task 221 on cpu 2:
   debug_spin_lock_before kernel/locking/spinlock_debug.c:85 [inline]
   do_raw_spin_lock+0x9b/0x210 kernel/locking/spinlock_debug.c:112
   __raw_spin_lock include/linux/spinlock_api_smp.h:143 [inline]
   _raw_spin_lock+0x39/0x40 kernel/locking/spinlock.c:151
   spin_lock include/linux/spinlock.h:338 [inline]
   get_partial_node.isra.0.part.0+0x32/0x2f0 mm/slub.c:1873
   get_partial_node mm/slub.c:1870 [inline]
  

  write to 0xffff8ab24f403c48 of 4 bytes by task 167 on cpu 3:
   debug_spin_unlock kernel/locking/spinlock_debug.c:103 [inline]
   do_raw_spin_unlock+0xc9/0x1a0 kernel/locking/spinlock_debug.c:138
   __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:159 [inline]
   _raw_spin_unlock_irqrestore+0x2d/0x50 kernel/locking/spinlock.c:191
   spin_unlock_irqrestore include/linux/spinlock.h:393 [inline]
   free_debug_processing+0x1b3/0x210 mm/slub.c:1214
   __slab_free+0x292/0x400 mm/slub.c:2864
  

As a side-effect, with KCSAN, this eventually locks up the console, most
likely due to deadlock, e.g. .. -> printk lock -> spinlock_debug ->
KCSAN detects data race -> kcsan_print_report() -> printk lock ->
deadlock.

This fix will 1) avoid the data races, and 2) allow using lock debugging
together with KCSAN.

Reported-by: Qian Cai 
Signed-off-by: Marco Elver 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Link: https://lkml.kernel.org/r/20191120155715.28089-1-elver@google.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

bpf: Fix passing modified ctx to ld/abs/ind instruction

2020-01-12T11:21:10+00:00

commit 6d4f151acf9a4f6fab09b615f246c717ddedcf0c upstream.

Anatoly has been fuzzing with kBdysch harness and reported a KASAN
slab oob in one of the outcomes:

  [...]
  [   77.359642] BUG: KASAN: slab-out-of-bounds in bpf_skb_load_helper_8_no_cache+0x71/0x130
  [   77.360463] Read of size 4 at addr ffff8880679bac68 by task bpf/406
  [   77.361119]
  [   77.361289] CPU: 2 PID: 406 Comm: bpf Not tainted 5.5.0-rc2-xfstests-00157-g2187f215eba #1
  [   77.362134] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
  [   77.362984] Call Trace:
  [   77.363249]  dump_stack+0x97/0xe0
  [   77.363603]  print_address_description.constprop.0+0x1d/0x220
  [   77.364251]  ? bpf_skb_load_helper_8_no_cache+0x71/0x130
  [   77.365030]  ? bpf_skb_load_helper_8_no_cache+0x71/0x130
  [   77.365860]  __kasan_report.cold+0x37/0x7b
  [   77.366365]  ? bpf_skb_load_helper_8_no_cache+0x71/0x130
  [   77.366940]  kasan_report+0xe/0x20
  [   77.367295]  bpf_skb_load_helper_8_no_cache+0x71/0x130
  [   77.367821]  ? bpf_skb_load_helper_8+0xf0/0xf0
  [   77.368278]  ? mark_lock+0xa3/0x9b0
  [   77.368641]  ? kvm_sched_clock_read+0x14/0x30
  [   77.369096]  ? sched_clock+0x5/0x10
  [   77.369460]  ? sched_clock_cpu+0x18/0x110
  [   77.369876]  ? bpf_skb_load_helper_8+0xf0/0xf0
  [   77.370330]  ___bpf_prog_run+0x16c0/0x28f0
  [   77.370755]  __bpf_prog_run32+0x83/0xc0
  [   77.371153]  ? __bpf_prog_run64+0xc0/0xc0
  [   77.371568]  ? match_held_lock+0x1b/0x230
  [   77.371984]  ? rcu_read_lock_held+0xa1/0xb0
  [   77.372416]  ? rcu_is_watching+0x34/0x50
  [   77.372826]  sk_filter_trim_cap+0x17c/0x4d0
  [   77.373259]  ? sock_kzfree_s+0x40/0x40
  [   77.373648]  ? __get_filter+0x150/0x150
  [   77.374059]  ? skb_copy_datagram_from_iter+0x80/0x280
  [   77.374581]  ? do_raw_spin_unlock+0xa5/0x140
  [   77.375025]  unix_dgram_sendmsg+0x33a/0xa70
  [   77.375459]  ? do_raw_spin_lock+0x1d0/0x1d0
  [   77.375893]  ? unix_peer_get+0xa0/0xa0
  [   77.376287]  ? __fget_light+0xa4/0xf0
  [   77.376670]  __sys_sendto+0x265/0x280
  [   77.377056]  ? __ia32_sys_getpeername+0x50/0x50
  [   77.377523]  ? lock_downgrade+0x350/0x350
  [   77.377940]  ? __sys_setsockopt+0x2a6/0x2c0
  [   77.378374]  ? sock_read_iter+0x240/0x240
  [   77.378789]  ? __sys_socketpair+0x22a/0x300
  [   77.379221]  ? __ia32_sys_socket+0x50/0x50
  [   77.379649]  ? mark_held_locks+0x1d/0x90
  [   77.380059]  ? trace_hardirqs_on_thunk+0x1a/0x1c
  [   77.380536]  __x64_sys_sendto+0x74/0x90
  [   77.380938]  do_syscall_64+0x68/0x2a0
  [   77.381324]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
  [   77.381878] RIP: 0033:0x44c070
  [...]

After further debugging, turns out while in case of other helper functions
we disallow passing modified ctx, the special case of ld/abs/ind instruction
which has similar semantics (except r6 being the ctx argument) is missing
such check. Modified ctx is impossible here as bpf_skb_load_helper_8_no_cache()
and others are expecting skb fields in original position, hence, add
check_ctx_reg() to reject any modified ctx. Issue was first introduced back
in f1174f77b50c ("bpf/verifier: rework value tracking").

Fixes: f1174f77b50c ("bpf/verifier: rework value tracking")
Reported-by: Anatoly Trosinenko 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20200106215157.3553-1-daniel@iogearbox.net
Signed-off-by: Greg Kroah-Hartman

kernel/module.c: wakeup processes in module_wq on module unload

2020-01-09T09:20:02+00:00

commit 5d603311615f612320bb77bd2a82553ef1ced5b7 upstream.

Fix the race between load and unload a kernel module.

sys_delete_module()
 try_stop_module()
  mod->state = _GOING
					add_unformed_module()
					 old = find_module_all()
					 (old->state == _GOING =>
					  wait_event_interruptible())

					 During pre-condition
					 finished_loading() rets 0
					 schedule()
					 (never gets waken up later)
 free_module()
  mod->state = _UNFORMED
   list_del_rcu(&mod->list)
   (dels mod from "modules" list)

return

The race above leads to modprobe hanging forever on loading
a module.

Error paths on loading module call wake_up_all(&module_wq) after
freeing module, so let's do the same on straight module unload.

Fixes: 6e6de3dee51a ("kernel/module.c: Only return -EEXIST for modules that have finished loading")
Reviewed-by: Prarit Bhargava 
Signed-off-by: Konstantin Khorenko 
Signed-off-by: Jessica Yu 
Signed-off-by: Greg Kroah-Hartman

ftrace: Avoid potential division by zero in function profiler

2020-01-09T09:20:01+00:00

commit e31f7939c1c27faa5d0e3f14519eaf7c89e8a69d upstream.

The ftrace_profile->counter is unsigned long and
do_div truncates it to 32 bits, which means it can test
non-zero and be truncated to zero for division.
Fix this issue by using div64_ul() instead.

Link: http://lkml.kernel.org/r/20200103030248.14516-1-wenyang@linux.alibaba.com

Cc: stable@vger.kernel.org
Fixes: e330b3bcd8319 ("tracing: Show sample std dev in function profiling")
Fixes: 34886c8bc590f ("tracing: add average time in function to function profiler")
Signed-off-by: Wen Yang 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

exit: panic before exit_mm() on global init exit

2020-01-09T09:20:01+00:00

commit 43cf75d96409a20ef06b756877a2e72b10a026fc upstream.

Currently, when global init and all threads in its thread-group have exited
we panic via:
do_exit()
-> exit_notify()
   -> forget_original_parent()
      -> find_child_reaper()
This makes it hard to extract a useable coredump for global init from a
kernel crashdump because by the time we panic exit_mm() will have already
released global init's mm.
This patch moves the panic futher up before exit_mm() is called. As was the
case previously, we only panic when global init and all its threads in the
thread-group have exited.

Signed-off-by: chenqiwu 
Acked-by: Christian Brauner 
Acked-by: Oleg Nesterov 
[christian.brauner@ubuntu.com: fix typo, rewrite commit message]
Link: https://lore.kernel.org/r/1576736993-10121-1-git-send-email-qiwuchen55@gmail.com
Signed-off-by: Christian Brauner 
Signed-off-by: Greg Kroah-Hartman

tracing: Fix endianness bug in histogram trigger

2020-01-09T09:20:00+00:00

commit fe6e096a5bbf73a142f09c72e7aa2835026eb1a3 upstream.

At least on PA-RISC and s390 synthetic histogram triggers are failing
selftests because trace_event_raw_event_synth() always writes a 64 bit
values, but the reader expects a field->size sized value. On little endian
machines this doesn't hurt, but on big endian this makes the reader always
read zero values.

Link: http://lore.kernel.org/linux-trace-devel/20191218074427.96184-4-svens@linux.ibm.com

Cc: stable@vger.kernel.org
Fixes: 4b147936fa509 ("tracing: Add support for 'synthetic' events")
Acked-by: Tom Zanussi 
Signed-off-by: Sven Schnelle 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

tracing: Have the histogram compare functions convert to u64 first

2020-01-09T09:20:00+00:00

commit 106f41f5a302cb1f36c7543fae6a05de12e96fa4 upstream.

The compare functions of the histogram code would be specific for the size
of the value being compared (byte, short, int, long long). It would
reference the value from the array via the type of the compare, but the
value was stored in a 64 bit number. This is fine for little endian
machines, but for big endian machines, it would end up comparing zeros or
all ones (depending on the sign) for anything but 64 bit numbers.

To fix this, first derference the value as a u64 then convert it to the type
being compared.

Link: http://lkml.kernel.org/r/20191211103557.7bed6928@gandalf.local.home

Cc: stable@vger.kernel.org
Fixes: 08d43a5fa063e ("tracing: Add lock-free tracing_map")
Acked-by: Tom Zanussi 
Reported-by: Sven Schnelle 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman