Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  perf tools: Fix sample size bit operations
  perf tools: Fix ommitted mmap data update on remap
  watchdog: Change the default timeout and configure nmi watchdog period based on watchdog_thresh
  watchdog: Disable watchdog when thresh is zero
  watchdog: Only disable/enable watchdog if neccessary
  watchdog: Fix rounding bug in get_sample_period()
  perf tools: Propagate event parse error handling
  perf tools: Robustify dynamic sample content fetch
  perf tools: Pre-check sample size before parsing
  perf tools: Move evlist sample helpers to evlist area
  perf tools: Remove junk code in mmap size handling
  perf tools: Check we are able to read the event size on mmap

18 files changed, 216 insertions, 100 deletions

diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
index 5260fe91bcb6..d5e57db0f7be 100644
--- a/arch/x86/kernel/apic/hw_nmi.c
+++ b/arch/x86/kernel/apic/hw_nmi.c
@@ -19,9 +19,9 @@
 #include <linux/delay.h>
 
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
-u64 hw_nmi_get_sample_period(void)
+u64 hw_nmi_get_sample_period(int watchdog_thresh)
 {
-        return (u64)(cpu_khz) * 1000 * 60;
+        return (u64)(cpu_khz) * 1000 * watchdog_thresh;
 }
 #endif
 
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index c536f8545f74..2d304efc89df 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -45,11 +45,12 @@ static inline bool trigger_all_cpu_backtrace(void)
 
 #ifdef CONFIG_LOCKUP_DETECTOR
 int hw_nmi_is_cpu_stuck(struct pt_regs *);
-u64 hw_nmi_get_sample_period(void);
+u64 hw_nmi_get_sample_period(int watchdog_thresh);
 extern int watchdog_enabled;
+extern int watchdog_thresh;
 struct ctl_table;
-extern int proc_dowatchdog_enabled(struct ctl_table *, int ,
-                        void __user *, size_t *, loff_t *);
+extern int proc_dowatchdog(struct ctl_table *, int ,
+                           void __user *, size_t *, loff_t *);
 #endif
 
 #endif
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 885c4f242ad7..340f5ee57334 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -315,7 +315,6 @@ extern int proc_dowatchdog_thresh(struct ctl_table *table, int write,
                                   void __user *buffer,
                                   size_t *lenp, loff_t *ppos);
 extern unsigned int  softlockup_panic;
-extern int softlockup_thresh;
 void lockup_detector_init(void);
 #else
 static inline void touch_softlockup_watchdog(void)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index c0bb32414b17..3dd0c46fa3bb 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -730,14 +730,16 @@ static struct ctl_table kern_table[] = {
                 .data           = &watchdog_enabled,
                 .maxlen         = sizeof (int),
                 .mode           = 0644,
-                .proc_handler   = proc_dowatchdog_enabled,
+                .proc_handler   = proc_dowatchdog,
+                .extra1         = &zero,
+                .extra2         = &one,
         },
         {
                 .procname       = "watchdog_thresh",
-                .data           = &softlockup_thresh,
+                .data           = &watchdog_thresh,
                 .maxlen         = sizeof(int),
                 .mode           = 0644,
-                .proc_handler   = proc_dowatchdog_thresh,
+                .proc_handler   = proc_dowatchdog,
                 .extra1         = &neg_one,
                 .extra2         = &sixty,
         },
@@ -755,7 +757,9 @@ static struct ctl_table kern_table[] = {
                 .data           = &watchdog_enabled,
                 .maxlen         = sizeof (int),
                 .mode           = 0644,
-                .proc_handler   = proc_dowatchdog_enabled,
+                .proc_handler   = proc_dowatchdog,
+                .extra1         = &zero,
+                .extra2         = &one,
         },
 #endif
 #if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86)
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 14733d4d156b..6e63097fa73a 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -28,7 +28,7 @@
 #include <linux/perf_event.h>
 
 int watchdog_enabled = 1;
-int __read_mostly softlockup_thresh = 60;
+int __read_mostly watchdog_thresh = 10;
 
 static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
 static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
@@ -91,6 +91,17 @@ static int __init nosoftlockup_setup(char *str)
 __setup("nosoftlockup", nosoftlockup_setup);
 /*  */
 
+/*
+ * Hard-lockup warnings should be triggered after just a few seconds. Soft-
+ * lockups can have false positives under extreme conditions. So we generally
+ * want a higher threshold for soft lockups than for hard lockups. So we couple
+ * the thresholds with a factor: we make the soft threshold twice the amount of
+ * time the hard threshold is.
+ */
+static int get_softlockup_thresh()
+{
+        return watchdog_thresh * 2;
+}
 
 /*
  * Returns seconds, approximately.  We don't need nanosecond
@@ -105,12 +116,12 @@ static unsigned long get_timestamp(int this_cpu)
 static unsigned long get_sample_period(void)
 {
         /*
-         * convert softlockup_thresh from seconds to ns
+         * convert watchdog_thresh from seconds to ns
          * the divide by 5 is to give hrtimer 5 chances to
          * increment before the hardlockup detector generates
          * a warning
          */
-        return softlockup_thresh / 5 * NSEC_PER_SEC;
+        return get_softlockup_thresh() * (NSEC_PER_SEC / 5);
 }
 
 /* Commands for resetting the watchdog */
@@ -182,7 +193,7 @@ static int is_softlockup(unsigned long touch_ts)
         unsigned long now = get_timestamp(smp_processor_id());
 
         /* Warn about unreasonable delays: */
-        if (time_after(now, touch_ts + softlockup_thresh))
+        if (time_after(now, touch_ts + get_softlockup_thresh()))
                 return now - touch_ts;
 
         return 0;
@@ -359,7 +370,7 @@ static int watchdog_nmi_enable(int cpu)
 
         /* Try to register using hardware perf events */
         wd_attr = &wd_hw_attr;
-        wd_attr->sample_period = hw_nmi_get_sample_period();
+        wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);
         event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback);
         if (!IS_ERR(event)) {
                 printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");
@@ -501,28 +512,25 @@ static void watchdog_disable_all_cpus(void)
 /* sysctl functions */
 #ifdef CONFIG_SYSCTL
 /*
- * proc handler for /proc/sys/kernel/nmi_watchdog
+ * proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh
  */
 
-int proc_dowatchdog_enabled(struct ctl_table *table, int write,
-                     void __user *buffer, size_t *length, loff_t *ppos)
+int proc_dowatchdog(struct ctl_table *table, int write,
+                    void __user *buffer, size_t *lenp, loff_t *ppos)
 {
-        proc_dointvec(table, write, buffer, length, ppos);
+        int ret;
 
-        if (write) {
-                if (watchdog_enabled)
-                        watchdog_enable_all_cpus();
-                else
-                        watchdog_disable_all_cpus();
-        }
-        return 0;
-}
+        ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+        if (ret || !write)
+                goto out;
 
-int proc_dowatchdog_thresh(struct ctl_table *table, int write,
-                             void __user *buffer,
-                             size_t *lenp, loff_t *ppos)
-{
-        return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+        if (watchdog_enabled && watchdog_thresh)
+                watchdog_enable_all_cpus();
+        else
+                watchdog_disable_all_cpus();
+
+out:
+        return ret;
 }
 #endif /* CONFIG_SYSCTL */
 
diff --git a/tools/perf/builtin-test.c b/tools/perf/builtin-test.c
index 2f9a337b182f..b67186228c89 100644
--- a/tools/perf/builtin-test.c
+++ b/tools/perf/builtin-test.c
@@ -474,6 +474,7 @@ static int test__basic_mmap(void)
         unsigned int nr_events[nsyscalls],
                      expected_nr_events[nsyscalls], i, j;
         struct perf_evsel *evsels[nsyscalls], *evsel;
+        int sample_size = perf_sample_size(attr.sample_type);
 
         for (i = 0; i < nsyscalls; ++i) {
                 char name[64];
@@ -558,7 +559,13 @@ static int test__basic_mmap(void)
                         goto out_munmap;
                 }
 
-                perf_event__parse_sample(event, attr.sample_type, false, &sample);
+                err = perf_event__parse_sample(event, attr.sample_type, sample_size,
+                                               false, &sample);
+                if (err) {
+                        pr_err("Can't parse sample, err = %d\n", err);
+                        goto out_munmap;
+                }
+
                 evsel = perf_evlist__id2evsel(evlist, sample.id);
                 if (evsel == NULL) {
                         pr_debug("event with id %" PRIu64
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index ebfc7cf5f63b..2d7934e9de38 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -805,9 +805,14 @@ static void perf_session__mmap_read_idx(struct perf_session *self, int idx)
 {
         struct perf_sample sample;
         union perf_event *event;
+        int ret;
 
         while ((event = perf_evlist__mmap_read(top.evlist, idx)) != NULL) {
-                perf_session__parse_sample(self, event, &sample);
+                ret = perf_session__parse_sample(self, event, &sample);
+                if (ret) {
+                        pr_err("Can't parse sample, err = %d\n", ret);
+                        continue;
+                }
 
                 if (event->header.type == PERF_RECORD_SAMPLE)
                         perf_event__process_sample(event, &sample, self);
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 1023f67633a4..252b72a5e59e 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -9,21 +9,21 @@
 #include "thread_map.h"
 
 static const char *perf_event__names[] = {
-        [0]                      = "TOTAL",
-        [PERF_RECORD_MMAP]       = "MMAP",
-        [PERF_RECORD_LOST]       = "LOST",
-        [PERF_RECORD_COMM]       = "COMM",
-        [PERF_RECORD_EXIT]       = "EXIT",
-        [PERF_RECORD_THROTTLE]   = "THROTTLE",
-        [PERF_RECORD_UNTHROTTLE] = "UNTHROTTLE",
-        [PERF_RECORD_FORK]       = "FORK",
-        [PERF_RECORD_READ]       = "READ",
-        [PERF_RECORD_SAMPLE]     = "SAMPLE",
-        [PERF_RECORD_HEADER_ATTR]        = "ATTR",
-        [PERF_RECORD_HEADER_EVENT_TYPE]  = "EVENT_TYPE",
-        [PERF_RECORD_HEADER_TRACING_DATA]        = "TRACING_DATA",
-        [PERF_RECORD_HEADER_BUILD_ID]    = "BUILD_ID",
-        [PERF_RECORD_FINISHED_ROUND]     = "FINISHED_ROUND",
+        [0]                                     = "TOTAL",
+        [PERF_RECORD_MMAP]                      = "MMAP",
+        [PERF_RECORD_LOST]                      = "LOST",
+        [PERF_RECORD_COMM]                      = "COMM",
+        [PERF_RECORD_EXIT]                      = "EXIT",
+        [PERF_RECORD_THROTTLE]                  = "THROTTLE",
+        [PERF_RECORD_UNTHROTTLE]                = "UNTHROTTLE",
+        [PERF_RECORD_FORK]                      = "FORK",
+        [PERF_RECORD_READ]                      = "READ",
+        [PERF_RECORD_SAMPLE]                    = "SAMPLE",
+        [PERF_RECORD_HEADER_ATTR]               = "ATTR",
+        [PERF_RECORD_HEADER_EVENT_TYPE]         = "EVENT_TYPE",
+        [PERF_RECORD_HEADER_TRACING_DATA]       = "TRACING_DATA",
+        [PERF_RECORD_HEADER_BUILD_ID]           = "BUILD_ID",
+        [PERF_RECORD_FINISHED_ROUND]            = "FINISHED_ROUND",
 };
 
 const char *perf_event__name(unsigned int id)
@@ -35,6 +35,22 @@ const char *perf_event__name(unsigned int id)
         return perf_event__names[id];
 }
 
+int perf_sample_size(u64 sample_type)
+{
+        u64 mask = sample_type & PERF_SAMPLE_MASK;
+        int size = 0;
+        int i;
+
+        for (i = 0; i < 64; i++) {
+                if (mask & (1UL << i))
+                        size++;
+        }
+
+        size *= sizeof(u64);
+
+        return size;
+}
+
 static struct perf_sample synth_sample = {
         .pid       = -1,
         .tid       = -1,
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index 9c35170fb379..c08332871408 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -56,6 +56,13 @@ struct read_event {
         u64 id;
 };
 
+
+#define PERF_SAMPLE_MASK                                \
+        (PERF_SAMPLE_IP | PERF_SAMPLE_TID |             \
+         PERF_SAMPLE_TIME | PERF_SAMPLE_ADDR |          \
+        PERF_SAMPLE_ID | PERF_SAMPLE_STREAM_ID |        \
+         PERF_SAMPLE_CPU | PERF_SAMPLE_PERIOD)
+
 struct sample_event {
         struct perf_event_header        header;
         u64 array[];
@@ -75,6 +82,8 @@ struct perf_sample {
         struct ip_callchain *callchain;
 };
 
+int perf_sample_size(u64 sample_type);
+
 #define BUILD_ID_SIZE 20
 
 struct build_id_event {
@@ -178,6 +187,7 @@ int perf_event__preprocess_sample(const union perf_event *self,
 const char *perf_event__name(unsigned int id);
 
 int perf_event__parse_sample(const union perf_event *event, u64 type,
-                             bool sample_id_all, struct perf_sample *sample);
+                             int sample_size, bool sample_id_all,
+                             struct perf_sample *sample);
 
 #endif /* __PERF_RECORD_H */
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 23eb22b05d27..50aa34879c33 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -459,3 +459,34 @@ int perf_evlist__set_filters(struct perf_evlist *evlist)
 
         return 0;
 }
+
+u64 perf_evlist__sample_type(struct perf_evlist *evlist)
+{
+        struct perf_evsel *pos;
+        u64 type = 0;
+
+        list_for_each_entry(pos, &evlist->entries, node) {
+                if (!type)
+                        type = pos->attr.sample_type;
+                else if (type != pos->attr.sample_type)
+                        die("non matching sample_type");
+        }
+
+        return type;
+}
+
+bool perf_evlist__sample_id_all(const struct perf_evlist *evlist)
+{
+        bool value = false, first = true;
+        struct perf_evsel *pos;
+
+        list_for_each_entry(pos, &evlist->entries, node) {
+                if (first) {
+                        value = pos->attr.sample_id_all;
+                        first = false;
+                } else if (value != pos->attr.sample_id_all)
+                        die("non matching sample_id_all");
+        }
+
+        return value;
+}
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 7109d7add14e..0a1ef1f051f0 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -66,4 +66,7 @@ int perf_evlist__create_maps(struct perf_evlist *evlist, pid_t target_pid,
 void perf_evlist__delete_maps(struct perf_evlist *evlist);
 int perf_evlist__set_filters(struct perf_evlist *evlist);
 
+u64 perf_evlist__sample_type(struct perf_evlist *evlist);
+bool perf_evlist__sample_id_all(const struct perf_evlist *evlist);
+
 #endif /* __PERF_EVLIST_H */
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index d6fd59beb860..ee0fe0dffa71 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -303,8 +303,20 @@ static int perf_event__parse_id_sample(const union perf_event *event, u64 type,
         return 0;
 }
 
+static bool sample_overlap(const union perf_event *event,
+                           const void *offset, u64 size)
+{
+        const void *base = event;
+
+        if (offset + size > base + event->header.size)
+                return true;
+
+        return false;
+}
+
 int perf_event__parse_sample(const union perf_event *event, u64 type,
-                             bool sample_id_all, struct perf_sample *data)
+                             int sample_size, bool sample_id_all,
+                             struct perf_sample *data)
 {
         const u64 *array;
 
@@ -319,6 +331,9 @@ int perf_event__parse_sample(const union perf_event *event, u64 type,
 
         array = event->sample.array;
 
+        if (sample_size + sizeof(event->header) > event->header.size)
+                return -EFAULT;
+
         if (type & PERF_SAMPLE_IP) {
                 data->ip = event->ip.ip;
                 array++;
@@ -369,14 +384,29 @@ int perf_event__parse_sample(const union perf_event *event, u64 type,
         }
 
         if (type & PERF_SAMPLE_CALLCHAIN) {
+                if (sample_overlap(event, array, sizeof(data->callchain->nr)))
+                        return -EFAULT;
+
                 data->callchain = (struct ip_callchain *)array;
+
+                if (sample_overlap(event, array, data->callchain->nr))
+                        return -EFAULT;
+
                 array += 1 + data->callchain->nr;
         }
 
         if (type & PERF_SAMPLE_RAW) {
                 u32 *p = (u32 *)array;
+
+                if (sample_overlap(event, array, sizeof(u32)))
+                        return -EFAULT;
+
                 data->raw_size = *p;
                 p++;
+
+                if (sample_overlap(event, p, data->raw_size))
+                        return -EFAULT;
+
                 data->raw_data = p;
         }
 
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 93862a8027ea..0717bebc7649 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -934,37 +934,6 @@ out_delete_evlist:
         return -ENOMEM;
 }
 
-u64 perf_evlist__sample_type(struct perf_evlist *evlist)
-{
-        struct perf_evsel *pos;
-        u64 type = 0;
-
-        list_for_each_entry(pos, &evlist->entries, node) {
-                if (!type)
-                        type = pos->attr.sample_type;
-                else if (type != pos->attr.sample_type)
-                        die("non matching sample_type");
-        }
-
-        return type;
-}
-
-bool perf_evlist__sample_id_all(const struct perf_evlist *evlist)
-{
-        bool value = false, first = true;
-        struct perf_evsel *pos;
-
-        list_for_each_entry(pos, &evlist->entries, node) {
-                if (first) {
-                        value = pos->attr.sample_id_all;
-                        first = false;
-                } else if (value != pos->attr.sample_id_all)
-                        die("non matching sample_id_all");
-        }
-
-        return value;
-}
-
 int perf_event__synthesize_attr(struct perf_event_attr *attr, u16 ids, u64 *id,
                                 perf_event__handler_t process,
                                 struct perf_session *session)
diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
index 456661d7f10e..1886256768a1 100644
--- a/tools/perf/util/header.h
+++ b/tools/perf/util/header.h
@@ -64,8 +64,6 @@ int perf_header__write_pipe(int fd);
 int perf_header__push_event(u64 id, const char *name);
 char *perf_header__find_event(u64 id);
 
-u64 perf_evlist__sample_type(struct perf_evlist *evlist);
-bool perf_evlist__sample_id_all(const struct perf_evlist *evlist);
 void perf_header__set_feat(struct perf_header *header, int feat);
 void perf_header__clear_feat(struct perf_header *header, int feat);
 bool perf_header__has_feat(const struct perf_header *header, int feat);
diff --git a/tools/perf/util/include/linux/list.h b/tools/perf/util/include/linux/list.h
index 99358d61e9a5..1d928a0ce997 100644
--- a/tools/perf/util/include/linux/list.h
+++ b/tools/perf/util/include/linux/list.h
@@ -1,4 +1,6 @@
 #include <linux/kernel.h>
+#include <linux/prefetch.h>
+
 #include "../../../../include/linux/list.h"
 
 #ifndef PERF_LIST_H
diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index b5c7d818001c..69436b3200a4 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -675,6 +675,7 @@ static PyObject *pyrf_evlist__read_on_cpu(struct pyrf_evlist *pevlist,
         union perf_event *event;
         int sample_id_all = 1, cpu;
         static char *kwlist[] = {"sample_id_all", NULL, NULL};
+        int err;
 
         if (!PyArg_ParseTupleAndKeywords(args, kwargs, "i|i", kwlist,
                                          &cpu, &sample_id_all))
@@ -690,11 +691,17 @@ static PyObject *pyrf_evlist__read_on_cpu(struct pyrf_evlist *pevlist,
                         return PyErr_NoMemory();
 
                 first = list_entry(evlist->entries.next, struct perf_evsel, node);
-                perf_event__parse_sample(event, first->attr.sample_type, sample_id_all,
-                                         &pevent->sample);
+                err = perf_event__parse_sample(event, first->attr.sample_type,
+                                               perf_sample_size(first->attr.sample_type),
+                                               sample_id_all, &pevent->sample);
+                if (err) {
+                        pr_err("Can't parse sample, err = %d\n", err);
+                        goto end;
+                }
+
                 return pyevent;
         }
-
+end:
         Py_INCREF(Py_None);
         return Py_None;
 }
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index fff66741f18d..64500fc78799 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -97,6 +97,7 @@ out:
 void perf_session__update_sample_type(struct perf_session *self)
 {
         self->sample_type = perf_evlist__sample_type(self->evlist);
+        self->sample_size = perf_sample_size(self->sample_type);
         self->sample_id_all = perf_evlist__sample_id_all(self->evlist);
         perf_session__id_header_size(self);
 }
@@ -479,6 +480,7 @@ static void flush_sample_queue(struct perf_session *s,
         struct perf_sample sample;
         u64 limit = os->next_flush;
         u64 last_ts = os->last_sample ? os->last_sample->timestamp : 0ULL;
+        int ret;
 
         if (!ops->ordered_samples || !limit)
                 return;
@@ -487,9 +489,12 @@ static void flush_sample_queue(struct perf_session *s,
                 if (iter->timestamp > limit)
                         break;
 
-                perf_session__parse_sample(s, iter->event, &sample);
-                perf_session_deliver_event(s, iter->event, &sample, ops,
-                                           iter->file_offset);
+                ret = perf_session__parse_sample(s, iter->event, &sample);
+                if (ret)
+                        pr_err("Can't parse sample, err = %d\n", ret);
+                else
+                        perf_session_deliver_event(s, iter->event, &sample, ops,
+                                                   iter->file_offset);
 
                 os->last_flush = iter->timestamp;
                 list_del(&iter->list);
@@ -805,7 +810,9 @@ static int perf_session__process_event(struct perf_session *session,
         /*
          * For all kernel events we get the sample data
          */
-        perf_session__parse_sample(session, event, &sample);
+        ret = perf_session__parse_sample(session, event, &sample);
+        if (ret)
+                return ret;
 
         /* Preprocess sample records - precheck callchains */
         if (perf_session__preprocess_sample(session, event, &sample))
@@ -953,6 +960,30 @@ out_err:
         return err;
 }
 
+static union perf_event *
+fetch_mmaped_event(struct perf_session *session,
+                   u64 head, size_t mmap_size, char *buf)
+{
+        union perf_event *event;
+
+        /*
+         * Ensure we have enough space remaining to read
+         * the size of the event in the headers.
+         */
+        if (head + sizeof(event->header) > mmap_size)
+                return NULL;
+
+        event = (union perf_event *)(buf + head);
+
+        if (session->header.needs_swap)
+                perf_event_header__bswap(&event->header);
+
+        if (head + event->header.size > mmap_size)
+                return NULL;
+
+        return event;
+}
+
 int __perf_session__process_events(struct perf_session *session,
                                    u64 data_offset, u64 data_size,
                                    u64 file_size, struct perf_event_ops *ops)
@@ -1007,15 +1038,8 @@ remap:
         file_pos = file_offset + head;
 
 more:
-        event = (union perf_event *)(buf + head);
-
-        if (session->header.needs_swap)
-                perf_event_header__bswap(&event->header);
-        size = event->header.size;
-        if (size == 0)
-                size = 8;
-
-        if (head + event->header.size > mmap_size) {
+        event = fetch_mmaped_event(session, head, mmap_size, buf);
+        if (!event) {
                 if (mmaps[map_idx]) {
                         munmap(mmaps[map_idx], mmap_size);
                         mmaps[map_idx] = NULL;
diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h
index 8daaa2d15396..66d4e1490879 100644
--- a/tools/perf/util/session.h
+++ b/tools/perf/util/session.h
@@ -43,6 +43,7 @@ struct perf_session {
          */
         struct hists            hists;
         u64                     sample_type;
+        int                     sample_size;
         int                     fd;
         bool                    fd_pipe;
         bool                    repipe;
@@ -159,6 +160,7 @@ static inline int perf_session__parse_sample(struct perf_session *session,
                                              struct perf_sample *sample)
 {
         return perf_event__parse_sample(event, session->sample_type,
+                                        session->sample_size,
                                         session->sample_id_all, sample);
 }