2 files changed, 25 insertions, 1 deletions

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index c0b785b50849..020323af3364 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -722,6 +722,27 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
         return 0;
 }
 
+/*
+ * Basic modifier sanity check to validate it contains only one
+ * instance of any modifier (apart from 'p') present.
+ */
+static int check_modifier(char *str)
+{
+        char *p = str;
+
+        /* The sizeof includes 0 byte as well. */
+        if (strlen(str) > (sizeof("ukhGHppp") - 1))
+                return -1;
+
+        while (*p) {
+                if (*p != 'p' && strchr(p + 1, *p))
+                        return -1;
+                p++;
+        }
+
+        return 0;
+}
+
 int parse_events__modifier_event(struct list_head *list, char *str, bool add)
 {
         struct perf_evsel *evsel;
@@ -730,6 +751,9 @@ int parse_events__modifier_event(struct list_head *list, char *str, bool add)
         if (str == NULL)
                 return 0;
 
+        if (check_modifier(str))
+                return -EINVAL;
+
         if (!add && get_event_modifier(&mod, str, NULL))
                 return -EINVAL;
 
diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
index 66959fab6634..e9d1134c2c68 100644
--- a/tools/perf/util/parse-events.l
+++ b/tools/perf/util/parse-events.l
@@ -82,7 +82,7 @@ num_hex		0x[a-fA-F0-9]+
 num_raw_hex     [a-fA-F0-9]+
 name            [a-zA-Z_*?][a-zA-Z0-9_*?]*
 name_minus      [a-zA-Z_*?][a-zA-Z0-9\-_*?]*
-modifier_event  [ukhpGH]{1,8}
+modifier_event  [ukhpGH]+
 modifier_bp     [rwx]{1,3}
 
 %%