On 10/2/13 7:46 AM, Jiri Olsa wrote:
The perf_evlist__mmap_read used 'union perf_event'
as a placeholder for event crossing the mmap boundary.
This is ok for sample shorter than ~PATH_MAX. However
we could grow up to the maximum sample size which is
16 bits max.
I hit this overflow issue when using 'perf top -G dwarf'
which produces sample with the size around 8192 bytes.
We could configure any valid sample size here using:
'-G dwarf,size'.
Using array with sample max size instead for the event
placeholder. Also adding another safe check for the
dynamic size of the user stack.
TODO: The 'struct perf_mmap' is quite big now, maybe we
could use some lazy allocation for event_copy size.
I was going to suggest just that -- dynamically handle the use of
event_copy. The below adds ~60k per mmap. Otherwise...
Acked-by: David Ahern <dsah...@gmail.com>
Signed-off-by: Jiri Olsa <jo...@redhat.com>
Cc: Corey Ashford <cjash...@linux.vnet.ibm.com>
Cc: David Ahern <dsah...@gmail.com>
Cc: Ingo Molnar <mi...@elte.hu>
Cc: Namhyung Kim <namhy...@kernel.org>
Cc: Paul Mackerras <pau...@samba.org>
Cc: Peter Zijlstra <a.p.zijls...@chello.nl>
Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
Cc: Frederic Weisbecker <fweis...@gmail.com>
---
tools/perf/util/event.h | 3 +++
tools/perf/util/evlist.c | 4 ++--
tools/perf/util/evlist.h | 2 +-
tools/perf/util/evsel.c | 3 +++
4 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index 9f50f88..2b8032a 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -75,6 +75,9 @@ struct throttle_event {
PERF_SAMPLE_CPU | PERF_SAMPLE_PERIOD | \
PERF_SAMPLE_IDENTIFIER)
+/* perf sample has 16 bits size limit */
+#define PERF_SAMPLE_MAX_SIZE (1 << 16)
+
struct sample_event {
struct perf_event_header header;
u64 array[];
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index f0d71a9..cb9523f 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -540,7 +540,7 @@ union perf_event *perf_evlist__mmap_read(struct perf_evlist
*evlist, int idx)
if ((old & md->mask) + size != ((old + size) & md->mask)) {
unsigned int offset = old;
unsigned int len = min(sizeof(*event), size), cpy;
- void *dst = &md->event_copy;
+ void *dst = md->event_copy;
do {
cpy = min(md->mask + 1 - (offset & md->mask),
len);
@@ -550,7 +550,7 @@ union perf_event *perf_evlist__mmap_read(struct perf_evlist
*evlist, int idx)
len -= cpy;
} while (len);
- event = &md->event_copy;
+ event = (union perf_event *) md->event_copy;
}
old += size;
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 871b55a..722618f 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -21,7 +21,7 @@ struct perf_mmap {
void *base;
int mask;
unsigned int prev;
- union perf_event event_copy;
+ char event_copy[PERF_SAMPLE_MAX_SIZE];
};
struct perf_evlist {
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 0ce9feb..aa20ee2 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1453,6 +1453,9 @@ int perf_evsel__parse_sample(struct perf_evsel *evsel,
union perf_event *event,
array = (void *)array + sz;
OVERFLOW_CHECK_u64(array);
data->user_stack.size = *array++;
+ if (WARN_ONCE(data->user_stack.size > sz,
+ "user stack dump failure\n"))
+ return -EFAULT;
}
}
--
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