linux.git/kernel/events, branch v4.13

Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2017-09-03T16:23:23+00:00

Pull perf fixes from Thomas Gleixner:

 - Prevent a potential inconistency in the perf user space access which
   might lead to evading sanity checks.

 - Prevent perf recording function trace entries twice

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/ftrace: Fix double traces of perf on ftrace:function
  perf/core: Fix potential double-fetch bug

mm, uprobes: fix multiple free of ->uprobes_state.xol_area

2017-08-31T23:33:15+00:00

Commit 7c051267931a ("mm, fork: make dup_mmap wait for mmap_sem for
write killable") made it possible to kill a forking task while it is
waiting to acquire its ->mmap_sem for write, in dup_mmap().

However, it was overlooked that this introduced an new error path before
the new mm_struct's ->uprobes_state.xol_area has been set to NULL after
being copied from the old mm_struct by the memcpy in dup_mm().  For a
task that has previously hit a uprobe tracepoint, this resulted in the
'struct xol_area' being freed multiple times if the task was killed at
just the right time while forking.

Fix it by setting ->uprobes_state.xol_area to NULL in mm_init() rather
than in uprobe_dup_mmap().

With CONFIG_UPROBE_EVENTS=y, the bug can be reproduced by the same C
program given by commit 2b7e8665b4ff ("fork: fix incorrect fput of
->exe_file causing use-after-free"), provided that a uprobe tracepoint
has been set on the fork_thread() function.  For example:

    $ gcc reproducer.c -o reproducer -lpthread
    $ nm reproducer | grep fork_thread
    0000000000400719 t fork_thread
    $ echo "p $PWD/reproducer:0x719" > /sys/kernel/debug/tracing/uprobe_events
    $ echo 1 > /sys/kernel/debug/tracing/events/uprobes/enable
    $ ./reproducer

Here is the use-after-free reported by KASAN:

    BUG: KASAN: use-after-free in uprobe_clear_state+0x1c4/0x200
    Read of size 8 at addr ffff8800320a8b88 by task reproducer/198

    CPU: 1 PID: 198 Comm: reproducer Not tainted 4.13.0-rc7-00015-g36fde05f3fb5 #255
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-20170228_101828-anatol 04/01/2014
    Call Trace:
     dump_stack+0xdb/0x185
     print_address_description+0x7e/0x290
     kasan_report+0x23b/0x350
     __asan_report_load8_noabort+0x19/0x20
     uprobe_clear_state+0x1c4/0x200
     mmput+0xd6/0x360
     do_exit+0x740/0x1670
     do_group_exit+0x13f/0x380
     get_signal+0x597/0x17d0
     do_signal+0x99/0x1df0
     exit_to_usermode_loop+0x166/0x1e0
     syscall_return_slowpath+0x258/0x2c0
     entry_SYSCALL_64_fastpath+0xbc/0xbe

    ...

    Allocated by task 199:
     save_stack_trace+0x1b/0x20
     kasan_kmalloc+0xfc/0x180
     kmem_cache_alloc_trace+0xf3/0x330
     __create_xol_area+0x10f/0x780
     uprobe_notify_resume+0x1674/0x2210
     exit_to_usermode_loop+0x150/0x1e0
     prepare_exit_to_usermode+0x14b/0x180
     retint_user+0x8/0x20

    Freed by task 199:
     save_stack_trace+0x1b/0x20
     kasan_slab_free+0xa8/0x1a0
     kfree+0xba/0x210
     uprobe_clear_state+0x151/0x200
     mmput+0xd6/0x360
     copy_process.part.8+0x605f/0x65d0
     _do_fork+0x1a5/0xbd0
     SyS_clone+0x19/0x20
     do_syscall_64+0x22f/0x660
     return_from_SYSCALL_64+0x0/0x7a

Note: without KASAN, you may instead see a "Bad page state" message, or
simply a general protection fault.

Link: http://lkml.kernel.org/r/20170830033303.17927-1-ebiggers3@gmail.com
Fixes: 7c051267931a ("mm, fork: make dup_mmap wait for mmap_sem for write killable")
Signed-off-by: Eric Biggers 
Reported-by: Oleg Nesterov 
Acked-by: Oleg Nesterov 
Cc: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Dmitry Vyukov 
Cc: Ingo Molnar 
Cc: Konstantin Khlebnikov 
Cc: Mark Rutland 
Cc: Michal Hocko 
Cc: Peter Zijlstra 
Cc: Vlastimil Babka 
Cc:     [4.7+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

perf/ftrace: Fix double traces of perf on ftrace:function

2017-08-29T11:29:29+00:00

When running perf on the ftrace:function tracepoint, there is a bug
which can be reproduced by:

  perf record -e ftrace:function -a sleep 20 &
  perf record -e ftrace:function ls
  perf script

              ls 10304 [005]   171.853235: ftrace:function:
  perf_output_begin
              ls 10304 [005]   171.853237: ftrace:function:
  perf_output_begin
              ls 10304 [005]   171.853239: ftrace:function:
  task_tgid_nr_ns
              ls 10304 [005]   171.853240: ftrace:function:
  task_tgid_nr_ns
              ls 10304 [005]   171.853242: ftrace:function:
  __task_pid_nr_ns
              ls 10304 [005]   171.853244: ftrace:function:
  __task_pid_nr_ns

We can see that all the function traces are doubled.

The problem is caused by the inconsistency of the register
function perf_ftrace_event_register() with the probe function
perf_ftrace_function_call(). The former registers one probe
for every perf_event. And the latter handles all perf_events
on the current cpu. So when two perf_events on the current cpu,
the traces of them will be doubled.

So this patch adds an extra parameter "event" for perf_tp_event,
only send sample data to this event when it's not NULL.

Signed-off-by: Zhou Chengming 
Reviewed-by: Jiri Olsa 
Acked-by: Steven Rostedt (VMware) 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: acme@kernel.org
Cc: alexander.shishkin@linux.intel.com
Cc: huawei.libin@huawei.com
Link: http://lkml.kernel.org/r/1503668977-12526-1-git-send-email-zhouchengming1@huawei.com
Signed-off-by: Ingo Molnar

perf/core: Fix potential double-fetch bug

2017-08-29T11:26:22+00:00

While examining the kernel source code, I found a dangerous operation that
could turn into a double-fetch situation (a race condition bug) where the same
userspace memory region are fetched twice into kernel with sanity checks after
the first fetch while missing checks after the second fetch.

  1. The first fetch happens in line 9573 get_user(size, &uattr->size).

  2. Subsequently the 'size' variable undergoes a few sanity checks and
     transformations (line 9577 to 9584).

  3. The second fetch happens in line 9610 copy_from_user(attr, uattr, size)

  4. Given that 'uattr' can be fully controlled in userspace, an attacker can
     race condition to override 'uattr->size' to arbitrary value (say, 0xFFFFFFFF)
     after the first fetch but before the second fetch. The changed value will be
     copied to 'attr->size'.

  5. There is no further checks on 'attr->size' until the end of this function,
     and once the function returns, we lose the context to verify that 'attr->size'
     conforms to the sanity checks performed in step 2 (line 9577 to 9584).

  6. My manual analysis shows that 'attr->size' is not used elsewhere later,
     so, there is no working exploit against it right now. However, this could
     easily turns to an exploitable one if careless developers start to use
     'attr->size' later.

To fix this, override 'attr->size' from the second fetch to the one from the
first fetch, regardless of what is actually copied in.

In this way, it is assured that 'attr->size' is consistent with the checks
performed after the first fetch.

Signed-off-by: Meng Xu 
Acked-by: Peter Zijlstra 
Cc: Linus Torvalds 
Cc: Thomas Gleixner 
Cc: acme@kernel.org
Cc: alexander.shishkin@linux.intel.com
Cc: meng.xu@gatech.edu
Cc: sanidhya@gatech.edu
Cc: taesoo@gatech.edu
Link: http://lkml.kernel.org/r/1503522470-35531-1-git-send-email-meng.xu@gatech.edu
Signed-off-by: Ingo Molnar

perf/core: Fix group {cpu,task} validation

2017-08-25T09:00:34+00:00

Regardless of which events form a group, it does not make sense for the
events to target different tasks and/or CPUs, as this leaves the group
inconsistent and impossible to schedule. The core perf code assumes that
these are consistent across (successfully intialised) groups.

Core perf code only verifies this when moving SW events into a HW
context. Thus, we can violate this requirement for pure SW groups and
pure HW groups, unless the relevant PMU driver happens to perform this
verification itself. These mismatched groups subsequently wreak havoc
elsewhere.

For example, we handle watchpoints as SW events, and reserve watchpoint
HW on a per-CPU basis at pmu::event_init() time to ensure that any event
that is initialised is guaranteed to have a slot at pmu::add() time.
However, the core code only checks the group leader's cpu filter (via
event_filter_match()), and can thus install follower events onto CPUs
violating thier (mismatched) CPU filters, potentially installing them
into a CPU without sufficient reserved slots.

This can be triggered with the below test case, resulting in warnings
from arch backends.

  #define _GNU_SOURCE
  #include 
  #include 
  #include 
  #include 
  #include 
  #include 
  #include 

  static int perf_event_open(struct perf_event_attr *attr, pid_t pid, int cpu,
			   int group_fd, unsigned long flags)
  {
	return syscall(__NR_perf_event_open, attr, pid, cpu, group_fd, flags);
  }

  char watched_char;

  struct perf_event_attr wp_attr = {
	.type = PERF_TYPE_BREAKPOINT,
	.bp_type = HW_BREAKPOINT_RW,
	.bp_addr = (unsigned long)&watched_char,
	.bp_len = 1,
	.size = sizeof(wp_attr),
  };

  int main(int argc, char *argv[])
  {
	int leader, ret;
	cpu_set_t cpus;

	/*
	 * Force use of CPU0 to ensure our CPU0-bound events get scheduled.
	 */
	CPU_ZERO(&cpus);
	CPU_SET(0, &cpus);
	ret = sched_setaffinity(0, sizeof(cpus), &cpus);
	if (ret) {
		printf("Unable to set cpu affinity\n");
		return 1;
	}

	/* open leader event, bound to this task, CPU0 only */
	leader = perf_event_open(&wp_attr, 0, 0, -1, 0);
	if (leader < 0) {
		printf("Couldn't open leader: %d\n", leader);
		return 1;
	}

	/*
	 * Open a follower event that is bound to the same task, but a
	 * different CPU. This means that the group should never be possible to
	 * schedule.
	 */
	ret = perf_event_open(&wp_attr, 0, 1, leader, 0);
	if (ret < 0) {
		printf("Couldn't open mismatched follower: %d\n", ret);
		return 1;
	} else {
		printf("Opened leader/follower with mismastched CPUs\n");
	}

	/*
	 * Open as many independent events as we can, all bound to the same
	 * task, CPU0 only.
	 */
	do {
		ret = perf_event_open(&wp_attr, 0, 0, -1, 0);
	} while (ret >= 0);

	/*
	 * Force enable/disble all events to trigger the erronoeous
	 * installation of the follower event.
	 */
	printf("Opened all events. Toggling..\n");
	for (;;) {
		prctl(PR_TASK_PERF_EVENTS_DISABLE, 0, 0, 0, 0);
		prctl(PR_TASK_PERF_EVENTS_ENABLE, 0, 0, 0, 0);
	}

	return 0;
  }

Fix this by validating this requirement regardless of whether we're
moving events.

Signed-off-by: Mark Rutland 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Zhou Chengming 
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1498142498-15758-1-git-send-email-mark.rutland@arm.com
Signed-off-by: Ingo Molnar

perf/core: Fix time on IOC_ENABLE

2017-08-10T10:01:09+00:00

Vince reported that when we do IOC_ENABLE/IOC_DISABLE while the task
is SIGSTOP'ed state the timestamps go wobbly.

It turns out we indeed fail to correctly account time while in 'OFF'
state and doing IOC_ENABLE without getting scheduled in exposes the
problem.

Further thinking about this problem, it occurred to me that we can
suffer a similar fate when we migrate an uncore event between CPUs.
The perf_event_install() on the 'new' CPU will do add_event_to_ctx()
which will reset all the time stamp, resulting in a subsequent
update_event_times() to overwrite the total_time_* fields with smaller
values.

Reported-by: Vince Weaver 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Signed-off-by: Ingo Molnar

perf/x86: Fix RDPMC vs. mm_struct tracking

2017-08-10T10:01:08+00:00

Vince reported the following rdpmc() testcase failure:

 > Failing test case:
 >
 >	fd=perf_event_open();
 >	addr=mmap(fd);
 >	exec()  // without closing or unmapping the event
 >	fd=perf_event_open();
 >	addr=mmap(fd);
 >	rdpmc()	// GPFs due to rdpmc being disabled

The problem is of course that exec() plays tricks with what is
current->mm, only destroying the old mappings after having
installed the new mm.

Fix this confusion by passing along vma->vm_mm instead of relying on
current->mm.

Reported-by: Vince Weaver 
Tested-by: Vince Weaver 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Andy Lutomirski 
Cc: Arnaldo Carvalho de Melo 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: stable@vger.kernel.org
Fixes: 1e0fb9ec679c ("perf: Add pmu callbacks to track event mapping and unmapping")
Link: http://lkml.kernel.org/r/20170802173930.cstykcqefmqt7jau@hirez.programming.kicks-ass.net
[ Minor cleanups. ]
Signed-off-by: Ingo Molnar

Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2017-07-21T18:12:48+00:00

Pull perf fixes from Ingo Molnar:
 "Two hw-enablement patches, two race fixes, three fixes for regressions
  of semantics, plus a number of tooling fixes"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel: Add proper condition to run sched_task callbacks
  perf/core: Fix locking for children siblings group read
  perf/core: Fix scheduling regression of pinned groups
  perf/x86/intel: Fix debug_store reset field for freq events
  perf/x86/intel: Add Goldmont Plus CPU PMU support
  perf/x86/intel: Enable C-state residency events for Apollo Lake
  perf symbols: Accept zero as the kernel base address
  Revert "perf/core: Drop kernel samples even though :u is specified"
  perf annotate: Fix broken arrow at row 0 connecting jmp instruction to its target
  perf evsel: State in the default event name if attr.exclude_kernel is set
  perf evsel: Fix attr.exclude_kernel setting for default cycles:p

perf/core: Fix locking for children siblings group read

2017-07-21T07:54:23+00:00

We're missing ctx lock when iterating children siblings
within the perf_read path for group reading. Following
race and crash can happen:

User space doing read syscall on event group leader:

T1:
  perf_read
    lock event->ctx->mutex
    perf_read_group
      lock leader->child_mutex
      __perf_read_group_add(child)
        list_for_each_entry(sub, &leader->sibling_list, group_entry)

---->   sub might be invalid at this point, because it could
        get removed via perf_event_exit_task_context in T2

Child exiting and cleaning up its events:

T2:
  perf_event_exit_task_context
    lock ctx->mutex
    list_for_each_entry_safe(child_event, next, &child_ctx->event_list,...
      perf_event_exit_event(child)
        lock ctx->lock
        perf_group_detach(child)
        unlock ctx->lock

---->   child is removed from sibling_list without any sync
        with T1 path above

        ...
        free_event(child)

Before the child is removed from the leader's child_list,
(and thus is omitted from perf_read_group processing), we
need to ensure that perf_read_group touches child's
siblings under its ctx->lock.

Peter further notes:

| One additional note; this bug got exposed by commit:
|
|   ba5213ae6b88 ("perf/core: Correct event creation with PERF_FORMAT_GROUP")
|
| which made it possible to actually trigger this code-path.

Tested-by: Andi Kleen 
Signed-off-by: Jiri Olsa 
Acked-by: Peter Zijlstra (Intel) 
Cc: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Fixes: ba5213ae6b88 ("perf/core: Correct event creation with PERF_FORMAT_GROUP")
Link: http://lkml.kernel.org/r/20170720141455.2106-1-jolsa@kernel.org
Signed-off-by: Ingo Molnar

perf/core: Fix scheduling regression of pinned groups

2017-07-20T07:43:02+00:00

Vince Weaver reported:

> I was tracking down some regressions in my perf_event_test testsuite.
> Some of the tests broke in the 4.11-rc1 timeframe.
>
> I've bisected one of them, this report is about
>	tests/overflow/simul_oneshot_group_overflow
> This test creates an event group containing two sampling events, set
> to overflow to a signal handler (which disables and then refreshes the
> event).
>
> On a good kernel you get the following:
> 	Event perf::instructions with period 1000000
> 	Event perf::instructions with period 2000000
> 		fd 3 overflows: 946 (perf::instructions/1000000)
> 		fd 4 overflows: 473 (perf::instructions/2000000)
> 	Ending counts:
> 		Count 0: 946379875
> 		Count 1: 946365218
>
> With the broken kernels you get:
> 	Event perf::instructions with period 1000000
> 	Event perf::instructions with period 2000000
> 		fd 3 overflows: 938 (perf::instructions/1000000)
> 		fd 4 overflows: 318 (perf::instructions/2000000)
> 	Ending counts:
> 		Count 0: 946373080
> 		Count 1: 653373058

The root cause of the bug is that the following commit:

  487f05e18a ("perf/core: Optimize event rescheduling on active contexts")

erronously assumed that event's 'pinned' setting determines whether the
event belongs to a pinned group or not, but in fact, it's the group
leader's pinned state that matters.

This was discovered by Vince in the test case described above, where two instruction
counters are grouped, the group leader is pinned, but the other event is not;
in the regressed case the counters were off by 33% (the difference between events'
periods), but should be the same within the error margin.

Fix the problem by looking at the group leader's pinning.

Reported-by: Vince Weaver 
Tested-by: Vince Weaver 
Signed-off-by: Alexander Shishkin 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Thomas Gleixner 
Cc: stable@vger.kernel.org
Fixes: 487f05e18a ("perf/core: Optimize event rescheduling on active contexts")
Link: http://lkml.kernel.org/r/87lgnmvw7h.fsf@ashishki-desk.ger.corp.intel.com
Signed-off-by: Ingo Molnar