[PATCH 1/2 v4] perf sched: fix wrong conversion of task state

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From	Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>
Newsgroups	linux.kernel
Subject	[PATCH 1/2 v4] perf sched: fix wrong conversion of task state
Date	Mon, 01 Aug 2016 06:40:01 +0200
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Currently sched_out_state() converts the prev_state u64 bitmask to a char
using the bitmask as an index, which may cause invalid memory access.
This fixes the issue by using the __ffs() returned value as an index.

Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com>
Fixes: cdce9d738b91e ("perf sched: Add sched latency profiling")
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
---
Changes from v3:
  Added Fixes:
  Split the patch into 2 pieces.

 tools/perf/builtin-sched.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 0dfe8df..ce9bef6 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -897,9 +897,10 @@ static int thread_atoms_insert(struct perf_sched *sched, struct thread *thread)
 
 static char sched_out_state(u64 prev_state)
 {
-	const char *str = TASK_STATE_TO_CHAR_STR;
+	const char str[] = TASK_STATE_TO_CHAR_STR;
+	unsigned int bit = prev_state ? __ffs(prev_state) + 1 : 0;
 
-	return str[prev_state];
+	return bit < ARRAY_SIZE(str) - 1 ? str[bit] : '?';
 }
 
 static int
-- 
2.7.4

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[PATCH 1/2 v4] perf sched: fix wrong conversion of task state Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com> - 2016-08-01 06:40 +0200
  Re: [PATCH 1/2 v4] perf sched: fix wrong conversion of task state David Ahern <dsahern@gmail.com> - 2016-08-01 16:00 +0200
  Re: [PATCH 1/2 v4] perf sched: fix wrong conversion of task state Masami Hiramatsu <mhiramat@kernel.org> - 2016-08-02 15:20 +0200

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