linux-stable.git/kernel/trace, branch v4.19.37

kprobes: Mark ftrace mcount handler functions nokprobe

2019-04-27T07:36:37+00:00

commit fabe38ab6b2bd9418350284c63825f13b8a6abba upstream.

Mark ftrace mcount handler functions nokprobe since
probing on these functions with kretprobe pushes
return address incorrectly on kretprobe shadow stack.

Reported-by: Francis Deslauriers 
Tested-by: Andrea Righi 
Signed-off-by: Masami Hiramatsu 
Acked-by: Steven Rostedt 
Acked-by: Steven Rostedt (VMware) 
Cc: Linus Torvalds 
Cc: Mathieu Desnoyers 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/155094062044.6137.6419622920568680640.stgit@devbox
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

tracing: kdb: Fix ftdump to not sleep

2019-04-05T20:32:56+00:00

[ Upstream commit 31b265b3baaf55f209229888b7ffea523ddab366 ]

As reported back in 2016-11 [1], the "ftdump" kdb command triggers a
BUG for "sleeping function called from invalid context".

kdb's "ftdump" command wants to call ring_buffer_read_prepare() in
atomic context.  A very simple solution for this is to add allocation
flags to ring_buffer_read_prepare() so kdb can call it without
triggering the allocation error.  This patch does that.

Note that in the original email thread about this, it was suggested
that perhaps the solution for kdb was to either preallocate the buffer
ahead of time or create our own iterator.  I'm hoping that this
alternative of adding allocation flags to ring_buffer_read_prepare()
can be considered since it means I don't need to duplicate more of the
core trace code into "trace_kdb.c" (for either creating my own
iterator or re-preparing a ring allocator whose memory was already
allocated).

NOTE: another option for kdb is to actually figure out how to make it
reuse the existing ftrace_dump() function and totally eliminate the
duplication.  This sounds very appealing and actually works (the "sr
z" command can be seen to properly dump the ftrace buffer).  The
downside here is that ftrace_dump() fully consumes the trace buffer.
Unless that is changed I'd rather not use it because it means "ftdump
| grep xyz" won't be very useful to search the ftrace buffer since it
will throw away the whole trace on the first grep.  A future patch to
dump only the last few lines of the buffer will also be hard to
implement.

[1] https://lkml.kernel.org/r/20161117191605.GA21459@google.com

Link: http://lkml.kernel.org/r/20190308193205.213659-1-dianders@chromium.org

Reported-by: Brian Norris 
Signed-off-by: Douglas Anderson 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Sasha Levin

tracing/perf: Use strndup_user() instead of buggy open-coded version

2019-03-23T19:09:56+00:00

commit 83540fbc8812a580b6ad8f93f4c29e62e417687e upstream.

The first version of this method was missing the check for
`ret == PATH_MAX`; then such a check was added, but it didn't call kfree()
on error, so there was still a small memory leak in the error case.
Fix it by using strndup_user() instead of open-coding it.

Link: http://lkml.kernel.org/r/20190220165443.152385-1-jannh@google.com

Cc: Ingo Molnar 
Cc: stable@vger.kernel.org
Fixes: 0eadcc7a7bc0 ("perf/core: Fix perf_uprobe_init()")
Reviewed-by: Masami Hiramatsu 
Acked-by: Song Liu 
Signed-off-by: Jann Horn 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

tracing: Do not free iter->trace in fail path of tracing_open_pipe()

2019-03-23T19:09:56+00:00

commit e7f0c424d0806b05d6f47be9f202b037eb701707 upstream.

Commit d716ff71dd12 ("tracing: Remove taking of trace_types_lock in
pipe files") use the current tracer instead of the copy in
tracing_open_pipe(), but it forget to remove the freeing sentence in
the error path.

There's an error path that can call kfree(iter->trace) after the iter->trace
was assigned to tr->current_trace, which would be bad to free.

Link: http://lkml.kernel.org/r/1550060946-45984-1-git-send-email-yi.zhang@huawei.com

Cc: stable@vger.kernel.org
Fixes: d716ff71dd12 ("tracing: Remove taking of trace_types_lock in pipe files")
Signed-off-by: zhangyi (F) 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

tracing: Use strncpy instead of memcpy for string keys in hist triggers

2019-03-23T19:09:56+00:00

commit 9f0bbf3115ca9f91f43b7c74e9ac7d79f47fc6c2 upstream.

Because there may be random garbage beyond a string's null terminator,
it's not correct to copy the the complete character array for use as a
hist trigger key.  This results in multiple histogram entries for the
'same' string key.

So, in the case of a string key, use strncpy instead of memcpy to
avoid copying in the extra bytes.

Before, using the gdbus entries in the following hist trigger as an
example:

  # echo 'hist:key=comm' > /sys/kernel/debug/tracing/events/sched/sched_waking/trigger
  # cat /sys/kernel/debug/tracing/events/sched/sched_waking/hist

  ...

  { comm: ImgDecoder #4                      } hitcount:        203
  { comm: gmain                              } hitcount:        213
  { comm: gmain                              } hitcount:        216
  { comm: StreamTrans #73                    } hitcount:        221
  { comm: mozStorage #3                      } hitcount:        230
  { comm: gdbus                              } hitcount:        233
  { comm: StyleThread#5                      } hitcount:        253
  { comm: gdbus                              } hitcount:        256
  { comm: gdbus                              } hitcount:        260
  { comm: StyleThread#4                      } hitcount:        271

  ...

  # cat /sys/kernel/debug/tracing/events/sched/sched_waking/hist | egrep gdbus | wc -l
  51

After:

  # cat /sys/kernel/debug/tracing/events/sched/sched_waking/hist | egrep gdbus | wc -l
  1

Link: http://lkml.kernel.org/r/50c35ae1267d64eee975b8125e151e600071d4dc.1549309756.git.tom.zanussi@linux.intel.com

Cc: Namhyung Kim 
Cc: stable@vger.kernel.org
Fixes: 79e577cbce4c4 ("tracing: Support string type key properly")
Signed-off-by: Tom Zanussi 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

bpf: fix potential deadlock in bpf_prog_register

2019-03-13T21:02:36+00:00

[ Upstream commit e16ec34039c701594d55d08a5aa49ee3e1abc821 ]

Lockdep found a potential deadlock between cpu_hotplug_lock, bpf_event_mutex, and cpuctx_mutex:
[   13.007000] WARNING: possible circular locking dependency detected
[   13.007587] 5.0.0-rc3-00018-g2fa53f892422-dirty #477 Not tainted
[   13.008124] ------------------------------------------------------
[   13.008624] test_progs/246 is trying to acquire lock:
[   13.009030] 0000000094160d1d (tracepoints_mutex){+.+.}, at: tracepoint_probe_register_prio+0x2d/0x300
[   13.009770]
[   13.009770] but task is already holding lock:
[   13.010239] 00000000d663ef86 (bpf_event_mutex){+.+.}, at: bpf_probe_register+0x1d/0x60
[   13.010877]
[   13.010877] which lock already depends on the new lock.
[   13.010877]
[   13.011532]
[   13.011532] the existing dependency chain (in reverse order) is:
[   13.012129]
[   13.012129] -> #4 (bpf_event_mutex){+.+.}:
[   13.012582]        perf_event_query_prog_array+0x9b/0x130
[   13.013016]        _perf_ioctl+0x3aa/0x830
[   13.013354]        perf_ioctl+0x2e/0x50
[   13.013668]        do_vfs_ioctl+0x8f/0x6a0
[   13.014003]        ksys_ioctl+0x70/0x80
[   13.014320]        __x64_sys_ioctl+0x16/0x20
[   13.014668]        do_syscall_64+0x4a/0x180
[   13.015007]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
[   13.015469]
[   13.015469] -> #3 (&cpuctx_mutex){+.+.}:
[   13.015910]        perf_event_init_cpu+0x5a/0x90
[   13.016291]        perf_event_init+0x1b2/0x1de
[   13.016654]        start_kernel+0x2b8/0x42a
[   13.016995]        secondary_startup_64+0xa4/0xb0
[   13.017382]
[   13.017382] -> #2 (pmus_lock){+.+.}:
[   13.017794]        perf_event_init_cpu+0x21/0x90
[   13.018172]        cpuhp_invoke_callback+0xb3/0x960
[   13.018573]        _cpu_up+0xa7/0x140
[   13.018871]        do_cpu_up+0xa4/0xc0
[   13.019178]        smp_init+0xcd/0xd2
[   13.019483]        kernel_init_freeable+0x123/0x24f
[   13.019878]        kernel_init+0xa/0x110
[   13.020201]        ret_from_fork+0x24/0x30
[   13.020541]
[   13.020541] -> #1 (cpu_hotplug_lock.rw_sem){++++}:
[   13.021051]        static_key_slow_inc+0xe/0x20
[   13.021424]        tracepoint_probe_register_prio+0x28c/0x300
[   13.021891]        perf_trace_event_init+0x11f/0x250
[   13.022297]        perf_trace_init+0x6b/0xa0
[   13.022644]        perf_tp_event_init+0x25/0x40
[   13.023011]        perf_try_init_event+0x6b/0x90
[   13.023386]        perf_event_alloc+0x9a8/0xc40
[   13.023754]        __do_sys_perf_event_open+0x1dd/0xd30
[   13.024173]        do_syscall_64+0x4a/0x180
[   13.024519]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
[   13.024968]
[   13.024968] -> #0 (tracepoints_mutex){+.+.}:
[   13.025434]        __mutex_lock+0x86/0x970
[   13.025764]        tracepoint_probe_register_prio+0x2d/0x300
[   13.026215]        bpf_probe_register+0x40/0x60
[   13.026584]        bpf_raw_tracepoint_open.isra.34+0xa4/0x130
[   13.027042]        __do_sys_bpf+0x94f/0x1a90
[   13.027389]        do_syscall_64+0x4a/0x180
[   13.027727]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
[   13.028171]
[   13.028171] other info that might help us debug this:
[   13.028171]
[   13.028807] Chain exists of:
[   13.028807]   tracepoints_mutex --> &cpuctx_mutex --> bpf_event_mutex
[   13.028807]
[   13.029666]  Possible unsafe locking scenario:
[   13.029666]
[   13.030140]        CPU0                    CPU1
[   13.030510]        ----                    ----
[   13.030875]   lock(bpf_event_mutex);
[   13.031166]                                lock(&cpuctx_mutex);
[   13.031645]                                lock(bpf_event_mutex);
[   13.032135]   lock(tracepoints_mutex);
[   13.032441]
[   13.032441]  *** DEADLOCK ***
[   13.032441]
[   13.032911] 1 lock held by test_progs/246:
[   13.033239]  #0: 00000000d663ef86 (bpf_event_mutex){+.+.}, at: bpf_probe_register+0x1d/0x60
[   13.033909]
[   13.033909] stack backtrace:
[   13.034258] CPU: 1 PID: 246 Comm: test_progs Not tainted 5.0.0-rc3-00018-g2fa53f892422-dirty #477
[   13.034964] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014
[   13.035657] Call Trace:
[   13.035859]  dump_stack+0x5f/0x8b
[   13.036130]  print_circular_bug.isra.37+0x1ce/0x1db
[   13.036526]  __lock_acquire+0x1158/0x1350
[   13.036852]  ? lock_acquire+0x98/0x190
[   13.037154]  lock_acquire+0x98/0x190
[   13.037447]  ? tracepoint_probe_register_prio+0x2d/0x300
[   13.037876]  __mutex_lock+0x86/0x970
[   13.038167]  ? tracepoint_probe_register_prio+0x2d/0x300
[   13.038600]  ? tracepoint_probe_register_prio+0x2d/0x300
[   13.039028]  ? __mutex_lock+0x86/0x970
[   13.039337]  ? __mutex_lock+0x24a/0x970
[   13.039649]  ? bpf_probe_register+0x1d/0x60
[   13.039992]  ? __bpf_trace_sched_wake_idle_without_ipi+0x10/0x10
[   13.040478]  ? tracepoint_probe_register_prio+0x2d/0x300
[   13.040906]  tracepoint_probe_register_prio+0x2d/0x300
[   13.041325]  bpf_probe_register+0x40/0x60
[   13.041649]  bpf_raw_tracepoint_open.isra.34+0xa4/0x130
[   13.042068]  ? __might_fault+0x3e/0x90
[   13.042374]  __do_sys_bpf+0x94f/0x1a90
[   13.042678]  do_syscall_64+0x4a/0x180
[   13.042975]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[   13.043382] RIP: 0033:0x7f23b10a07f9
[   13.045155] RSP: 002b:00007ffdef42fdd8 EFLAGS: 00000202 ORIG_RAX: 0000000000000141
[   13.045759] RAX: ffffffffffffffda RBX: 00007ffdef42ff70 RCX: 00007f23b10a07f9
[   13.046326] RDX: 0000000000000070 RSI: 00007ffdef42fe10 RDI: 0000000000000011
[   13.046893] RBP: 00007ffdef42fdf0 R08: 0000000000000038 R09: 00007ffdef42fe10
[   13.047462] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
[   13.048029] R13: 0000000000000016 R14: 00007f23b1db4690 R15: 0000000000000000

Since tracepoints_mutex will be taken in tracepoint_probe_register/unregister()
there is no need to take bpf_event_mutex too.
bpf_event_mutex is protecting modifications to prog array used in kprobe/perf bpf progs.
bpf_raw_tracepoints don't need to take this mutex.

Fixes: c4f6699dfcb8 ("bpf: introduce BPF_RAW_TRACEPOINT")
Acked-by: Martin KaFai Lau 
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Sasha Levin

tracing: Fix event filters and triggers to handle negative numbers

2019-03-10T06:17:20+00:00

commit 6a072128d262d2b98d31626906a96700d1fc11eb upstream.

Then tracing syscall exit event it is extremely useful to filter exit
codes equal to some negative value, to react only to required errors.
But negative numbers does not work:

[root@snorch sys_exit_read]# echo "ret == -1" > filter
bash: echo: write error: Invalid argument
[root@snorch sys_exit_read]# cat filter
ret == -1
        ^
parse_error: Invalid value (did you forget quotes)?

Similar thing happens when setting triggers.

These is a regression in v4.17 introduced by the commit mentioned below,
testing without these commit shows no problem with negative numbers.

Link: http://lkml.kernel.org/r/20180823102534.7642-1-ptikhomirov@virtuozzo.com

Cc: stable@vger.kernel.org
Fixes: 80765597bc58 ("tracing: Rewrite filter logic to be simpler and faster")
Signed-off-by: Pavel Tikhomirov 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

tracing: Fix number of entries in trace header

2019-02-27T09:08:49+00:00

commit 9e7382153f80ba45a0bbcd540fb77d4b15f6e966 upstream.

The following commit

  441dae8f2f29 ("tracing: Add support for display of tgid in trace output")

removed the call to print_event_info() from print_func_help_header_irq()
which results in the ftrace header not reporting the number of entries
written in the buffer. As this wasn't the original intent of the patch,
re-introduce the call to print_event_info() to restore the orginal
behaviour.

Link: http://lkml.kernel.org/r/20190214152950.4179-1-quentin.perret@arm.com

Acked-by: Joel Fernandes 
Cc: stable@vger.kernel.org
Fixes: 441dae8f2f29 ("tracing: Add support for display of tgid in trace output")
Signed-off-by: Quentin Perret 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman

tracing/uprobes: Fix output for multiple string arguments

2019-02-20T09:25:48+00:00

commit 0722069a5374b904ec1a67f91249f90e1cfae259 upstream.

When printing multiple uprobe arguments as strings the output for the
earlier arguments would also include all later string arguments.

This is best explained in an example:

Consider adding a uprobe to a function receiving two strings as
parameters which is at offset 0xa0 in strlib.so and we want to print
both parameters when the uprobe is hit (on x86_64):

$ echo 'p:func /lib/strlib.so:0xa0 +0(%di):string +0(%si):string' > \
    /sys/kernel/debug/tracing/uprobe_events

When the function is called as func("foo", "bar") and we hit the probe,
the trace file shows a line like the following:

  [...] func: (0x7f7e683706a0) arg1="foobar" arg2="bar"

Note the extra "bar" printed as part of arg1. This behaviour stacks up
for additional string arguments.

The strings are stored in a dynamically growing part of the uprobe
buffer by fetch_store_string() after copying them from userspace via
strncpy_from_user(). The return value of strncpy_from_user() is then
directly used as the required size for the string. However, this does
not take the terminating null byte into account as the documentation
for strncpy_from_user() cleary states that it "[...] returns the
length of the string (not including the trailing NUL)" even though the
null byte will be copied to the destination.

Therefore, subsequent calls to fetch_store_string() will overwrite
the terminating null byte of the most recently fetched string with
the first character of the current string, leading to the
"accumulation" of strings in earlier arguments in the output.

Fix this by incrementing the return value of strncpy_from_user() by
one if we did not hit the maximum buffer size.

Link: http://lkml.kernel.org/r/20190116141629.5752-1-andreas.ziegler@fau.de

Cc: Ingo Molnar 
Cc: stable@vger.kernel.org
Fixes: 5baaa59ef09e ("tracing/probes: Implement 'memory' fetch method for uprobes")
Acked-by: Masami Hiramatsu 
Signed-off-by: Andreas Ziegler 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Masami Hiramatsu 
Signed-off-by: Greg Kroah-Hartman

tracing: uprobes: Fix typo in pr_fmt string

2019-02-15T07:10:11+00:00

commit ea6eb5e7d15e1838de335609994b4546e2abcaaf upstream.

The subsystem-specific message prefix for uprobes was also
"trace_kprobe: " instead of "trace_uprobe: " as described in
the original commit message.

Link: http://lkml.kernel.org/r/20190117133023.19292-1-andreas.ziegler@fau.de

Cc: Ingo Molnar 
Cc: stable@vger.kernel.org
Acked-by: Masami Hiramatsu 
Fixes: 7257634135c24 ("tracing/probe: Show subsystem name in messages")
Signed-off-by: Andreas Ziegler 
Signed-off-by: Steven Rostedt (VMware) 
Signed-off-by: Greg Kroah-Hartman