diff options
author | Jiri Olsa <jolsa@redhat.com> | 2019-02-04 13:35:32 +0100 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2019-02-11 11:46:43 +0100 |
commit | 81ec3f3c4c4d78f2d3b6689c9816bfbdf7417dbb (patch) | |
tree | 7bfea72789e3aad5263cbb7859ce1e97a05a940d /kernel | |
parent | d13937116f1e82bf508a6325111b322c30c85eb9 (diff) | |
download | linux-81ec3f3c4c4d78f2d3b6689c9816bfbdf7417dbb.tar.bz2 |
perf/x86: Add check_period PMU callback
Vince (and later on Ravi) reported crashes in the BTS code during
fuzzing with the following backtrace:
general protection fault: 0000 [#1] SMP PTI
...
RIP: 0010:perf_prepare_sample+0x8f/0x510
...
Call Trace:
<IRQ>
? intel_pmu_drain_bts_buffer+0x194/0x230
intel_pmu_drain_bts_buffer+0x160/0x230
? tick_nohz_irq_exit+0x31/0x40
? smp_call_function_single_interrupt+0x48/0xe0
? call_function_single_interrupt+0xf/0x20
? call_function_single_interrupt+0xa/0x20
? x86_schedule_events+0x1a0/0x2f0
? x86_pmu_commit_txn+0xb4/0x100
? find_busiest_group+0x47/0x5d0
? perf_event_set_state.part.42+0x12/0x50
? perf_mux_hrtimer_restart+0x40/0xb0
intel_pmu_disable_event+0xae/0x100
? intel_pmu_disable_event+0xae/0x100
x86_pmu_stop+0x7a/0xb0
x86_pmu_del+0x57/0x120
event_sched_out.isra.101+0x83/0x180
group_sched_out.part.103+0x57/0xe0
ctx_sched_out+0x188/0x240
ctx_resched+0xa8/0xd0
__perf_event_enable+0x193/0x1e0
event_function+0x8e/0xc0
remote_function+0x41/0x50
flush_smp_call_function_queue+0x68/0x100
generic_smp_call_function_single_interrupt+0x13/0x30
smp_call_function_single_interrupt+0x3e/0xe0
call_function_single_interrupt+0xf/0x20
</IRQ>
The reason is that while event init code does several checks
for BTS events and prevents several unwanted config bits for
BTS event (like precise_ip), the PERF_EVENT_IOC_PERIOD allows
to create BTS event without those checks being done.
Following sequence will cause the crash:
If we create an 'almost' BTS event with precise_ip and callchains,
and it into a BTS event it will crash the perf_prepare_sample()
function because precise_ip events are expected to come
in with callchain data initialized, but that's not the
case for intel_pmu_drain_bts_buffer() caller.
Adding a check_period callback to be called before the period
is changed via PERF_EVENT_IOC_PERIOD. It will deny the change
if the event would become BTS. Plus adding also the limit_period
check as well.
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20190204123532.GA4794@krava
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/events/core.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index e5ede6918050..26d6edab051a 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4963,6 +4963,11 @@ static void __perf_event_period(struct perf_event *event, } } +static int perf_event_check_period(struct perf_event *event, u64 value) +{ + return event->pmu->check_period(event, value); +} + static int perf_event_period(struct perf_event *event, u64 __user *arg) { u64 value; @@ -4979,6 +4984,9 @@ static int perf_event_period(struct perf_event *event, u64 __user *arg) if (event->attr.freq && value > sysctl_perf_event_sample_rate) return -EINVAL; + if (perf_event_check_period(event, value)) + return -EINVAL; + event_function_call(event, __perf_event_period, &value); return 0; @@ -9391,6 +9399,11 @@ static int perf_pmu_nop_int(struct pmu *pmu) return 0; } +static int perf_event_nop_int(struct perf_event *event, u64 value) +{ + return 0; +} + static DEFINE_PER_CPU(unsigned int, nop_txn_flags); static void perf_pmu_start_txn(struct pmu *pmu, unsigned int flags) @@ -9691,6 +9704,9 @@ got_cpu_context: pmu->pmu_disable = perf_pmu_nop_void; } + if (!pmu->check_period) + pmu->check_period = perf_event_nop_int; + if (!pmu->event_idx) pmu->event_idx = perf_event_idx_default; |