[PATCH 11/11] perf: Avoid uninitialized sample type reference in __perf_event__output_id_sample

[Andi Kleen]

From: Andi Kleen <a...@linux.intel.com>

__perf_event__output_id_sample looks at data->type to decide
what to output.

A lot of of the custom output functions, for example perf_log_throttle
start with perf_event_header__init_id, which only initializes
the header when event->attr.sample_id_all is true.

But when this is false the output function is still called,
and will look at an uninitialized header.

I changed all the callers to perf_event_header__init_id
to __perf_event_header__init_id which unconditionally
initializes the header.

FWIW I'm not fully sure this is the correct fix and what the
exact semantics of sample_id_all are supposed to be.
Should it disable all throttling etc. messages?
Please review carefully.

Cc: mi...@kernel.org
Cc: eran...@google.com
Cc: pet...@infradead.org
Signed-off-by: Andi Kleen <a...@linux.intel.com>
---
 kernel/events/core.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index cb4238e..0b15209 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4732,7 +4732,7 @@ perf_event_read_event(struct perf_event *event,
        };
        int ret;
 
-       perf_event_header__init_id(&read_event.header, &sample, event);
+       __perf_event_header__init_id(&read_event.header, &sample, event);
        ret = perf_output_begin(&handle, event, read_event.header.size);
        if (ret)
                return;
@@ -4837,7 +4837,7 @@ static void perf_event_task_output(struct perf_event 
*event,
        if (!perf_event_task_match(event))
                return;
 
-       perf_event_header__init_id(&task_event->event_id.header, &sample, 
event);
+       __perf_event_header__init_id(&task_event->event_id.header, &sample, 
event);
 
        ret = perf_output_begin(&handle, event,
                                task_event->event_id.header.size);
@@ -4931,7 +4931,7 @@ static void perf_event_comm_output(struct perf_event 
*event,
        if (!perf_event_comm_match(event))
                return;
 
-       perf_event_header__init_id(&comm_event->event_id.header, &sample, 
event);
+       __perf_event_header__init_id(&comm_event->event_id.header, &sample, 
event);
        ret = perf_output_begin(&handle, event,
                                comm_event->event_id.header.size);
 
@@ -5063,7 +5063,7 @@ static void perf_event_mmap_output(struct perf_event 
*event,
                mmap_event->event_id.header.size += 
sizeof(mmap_event->ino_generation);
        }
 
-       perf_event_header__init_id(&mmap_event->event_id.header, &sample, 
event);
+       __perf_event_header__init_id(&mmap_event->event_id.header, &sample, 
event);
        ret = perf_output_begin(&handle, event,
                                mmap_event->event_id.header.size);
        if (ret)
@@ -5237,7 +5237,7 @@ static void perf_log_throttle(struct perf_event *event, 
int enable)
        if (enable)
                throttle_event.header.type = PERF_RECORD_UNTHROTTLE;
 
-       perf_event_header__init_id(&throttle_event.header, &sample, event);
+       __perf_event_header__init_id(&throttle_event.header, &sample, event);
 
        ret = perf_output_begin(&handle, event,
                                throttle_event.header.size);
-- 
1.8.3.1

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