linux-kernel - [PATCH V8 15/25] perf tools: Validate config term maximum value

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Date:	Fri, 17 Jul 2015 19:33:50 +0300
From:	Adrian Hunter <adrian.hunter@...el.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
	Jiri Olsa <jolsa@...hat.com>
Subject: [PATCH V8 15/25] perf tools: Validate config term maximum value

Currently the value of a PMU config term is silently
truncated if it is too big. This is an impediment to
validating the value for other criteria later on i.e.
the user provides an invalid value that gets truncated
to a valid one.

The maximum value validation is only done for the
parser where the error is passed back to the user. In
other cases the silent truncation continues so as not
to affect tools that perhaps rely on it.

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 tools/perf/util/pmu.c | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index d26ff0ab8410..29797fd9bedc 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -585,6 +585,18 @@ static void pmu_format_value(unsigned long *format, __u64 value, __u64 *v,
 	}
 }
 
+static __u64 pmu_format_max_value(const unsigned long *format)
+{
+	int w;
+
+	w = bitmap_weight(format, PERF_PMU_FORMAT_BITS);
+	if (!w)
+		return 0;
+	if (w < 64)
+		return (1ULL << w) - 1;
+	return -1;
+}
+
 /*
  * Term is a string term, and might be a param-term. Try to look up it's value
  * in the remaining terms.
@@ -658,7 +670,7 @@ static int pmu_config_term(struct list_head *formats,
 {
 	struct perf_pmu_format *format;
 	__u64 *vp;
-	__u64 val;
+	__u64 val, max_val;
 
 	/*
 	 * If this is a parameter we've already used for parameterized-eval,
@@ -724,6 +736,22 @@ static int pmu_config_term(struct list_head *formats,
 	} else
 		return -EINVAL;
 
+	max_val = pmu_format_max_value(format->bits);
+	if (val > max_val) {
+		if (err) {
+			err->idx = term->err_val;
+			if (asprintf(&err->str,
+				     "value too big for format, maximum is %llu",
+				     (unsigned long long)max_val) < 0)
+				err->str = strdup("value too big for format");
+			return -EINVAL;
+		}
+		/*
+		 * Assume we don't care if !err, in which case the value will be
+		 * silently truncated.
+		 */
+	}
+
 	pmu_format_value(format->bits, val, vp, zero);
 	return 0;
 }
-- 
1.9.1

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