From: Jiri Olsa <[email protected]> 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. Signed-off-by: Jiri Olsa <[email protected]> Acked-by: David Ahern <[email protected]> Cc: Corey Ashford <[email protected]> Cc: David Ahern <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Peter Zijlstra <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Arnaldo Carvalho de Melo <[email protected]> --- 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 9b7d4d333111..752709ccfb00 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 f0d71a9d49f4..cb9523f50a37 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 871b55ab5dee..722618f84c53 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 abe69af58b62..bfebc1ea3c51 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -1456,6 +1456,9 @@ 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; } } -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
