linux-kernel - [PATCH 2/3] perf ui/tui: Fix off-by-one in hist_browser__update_nr

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Message-Id: <1397721206-15393-3-git-send-email-namhyung@kernel.org>
Date:	Thu, 17 Apr 2014 16:53:25 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Jiri Olsa <jolsa@...hat.com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...nel.org>,
	Paul Mackerras <paulus@...ba.org>,
	Namhyung Kim <namhyung.kim@....com>,
	Namhyung Kim <namhyung@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Andi Kleen <andi@...stfloor.org>
Subject: [PATCH 2/3] perf ui/tui: Fix off-by-one in hist_browser__update_nr_entries()

The nr_entries variable is increased inside the loop in the function
but it also counts when hists__filter_entries() returns NULL.  Thus
the end result will have actual count + 1.

It'd become a problem especially there's no entry at all - it'd get a
segfault during referencing a NULL pointer.

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/ui/browsers/hists.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index 4d416984c59d..e86b95cc55db 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -1349,9 +1349,10 @@ static void hist_browser__update_pcnt_entries(struct hist_browser *hb)
 	struct rb_node *nd = rb_first(&hb->hists->entries);
 
 	while (nd) {
-		nr_entries++;
 		nd = hists__filter_entries(rb_next(nd), hb->hists,
 					   hb->min_pcnt);
+		if (nd)
+			nr_entries++;
 	}
 
 	hb->nr_pcnt_entries = nr_entries;
-- 
1.9.2

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