linux-kernel - [PATCH 25/26] perf tools: Validate config term maximum value

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Date:	Thu,  6 Aug 2015 22:58:34 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	linux-kernel@...r.kernel.org,
	Adrian Hunter <adrian.hunter@...el.com>,
	Jiri Olsa <jolsa@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 25/26] perf tools: Validate config term maximum value

From: Adrian Hunter <adrian.hunter@...el.com>

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>
Cc: Jiri Olsa <jolsa@...hat.com>
Link: http://lkml.kernel.org/r/1437150840-31811-16-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.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 c548ec89c8bc..d4b0e6454bc6 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -589,6 +589,18 @@ 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.
@@ -662,7 +674,7 @@ 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,
@@ -728,6 +740,22 @@ 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;
 }
-- 
2.1.0

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