[tip: perf/core] perf header: Add check for unexpected use of reserved membrs in event attr

[tip-bot2 for Kan Liang]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     277ce1efa7b504873cd32a4106654836c2f80e1b
Gitweb:        https://git.kernel.org/tip/277ce1efa7b504873cd32a4106654836c2f80e1b
Author:        Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
AuthorDate:    Fri, 28 Feb 2020 08:30:02 -08:00
Committer:     Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitterDate: Mon, 09 Mar 2020 21:43:24 -03:00

perf header: Add check for unexpected use of reserved membrs in event attr

The perf.data may be generated by a newer version of perf tool, which
support new input bits in attr, e.g. new bit for branch_sample_type.

The perf.data may be parsed by an older version of perf tool later.  The
old perf tool may parse the perf.data incorrectly. There is no warning
message for this case.

Current perf header never check for unknown input bits in attr.

When read the event desc from header, check the stored event attr.  The
reserved bits, sample type, read format and branch sample type will be
checked.

Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Pavel Gerasimov <pavel.gerasimov@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@xxxxxxxxx>
Link: http://lkml.kernel.org/r/20200228163011.19358-4-kan.liang@xxxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/header.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 4246e74..acbd046 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1590,6 +1590,40 @@ static void free_event_desc(struct evsel *events)
 	free(events);
 }
 
+static bool perf_attr_check(struct perf_event_attr *attr)
+{
+	if (attr->__reserved_1 || attr->__reserved_2 || attr->__reserved_3) {
+		pr_warning("Reserved bits are set unexpectedly. "
+			   "Please update perf tool.\n");
+		return false;
+	}
+
+	if (attr->sample_type & ~(PERF_SAMPLE_MAX-1)) {
+		pr_warning("Unknown sample type (0x%llx) is detected. "
+			   "Please update perf tool.\n",
+			   attr->sample_type);
+		return false;
+	}
+
+	if (attr->read_format & ~(PERF_FORMAT_MAX-1)) {
+		pr_warning("Unknown read format (0x%llx) is detected. "
+			   "Please update perf tool.\n",
+			   attr->read_format);
+		return false;
+	}
+
+	if ((attr->sample_type & PERF_SAMPLE_BRANCH_STACK) &&
+	    (attr->branch_sample_type & ~(PERF_SAMPLE_BRANCH_MAX-1))) {
+		pr_warning("Unknown branch sample type (0x%llx) is detected. "
+			   "Please update perf tool.\n",
+			   attr->branch_sample_type);
+
+		return false;
+	}
+
+	return true;
+}
+
 static struct evsel *read_event_desc(struct feat_fd *ff)
 {
 	struct evsel *evsel, *events = NULL;
@@ -1634,6 +1668,9 @@ static struct evsel *read_event_desc(struct feat_fd *ff)
 
 		memcpy(&evsel->core.attr, buf, msz);
 
+		if (!perf_attr_check(&evsel->core.attr))
+			goto error;
+
 		if (do_read_u32(ff, &nr))
 			goto error;