[tip:tracing/core] tracing/filters: fix off-by-one bug

[tip-bot for Li Zefan <lizf@cn.fujitsu.com>]

Commit-ID:  5872144f64b34a5942f6b4acedc90b02de72c58b
Gitweb:     http://git.kernel.org/tip/5872144f64b34a5942f6b4acedc90b02de72c58b
Author:     Li Zefan <lizf@cn.fujitsu.com>
AuthorDate: Fri, 15 May 2009 11:07:56 +0800
Committer:  Steven Rostedt <rostedt@goodmis.org>
CommitDate: Thu, 14 May 2009 23:55:12 -0400

tracing/filters: fix off-by-one bug

We should leave the last slot for the ending '\0'.

[ Impact: fix possible crash when the length of an operand is 128 ]

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A0CDC8C.30602@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>


---
 kernel/trace/trace_events_filter.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 22c2998..a7430b1 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -736,7 +736,7 @@ static inline void clear_operand_string(struct filter_parse_state *ps)
 
 static inline int append_operand_char(struct filter_parse_state *ps, char c)
 {
-	if (ps->operand.tail == MAX_FILTER_STR_VAL)
+	if (ps->operand.tail == MAX_FILTER_STR_VAL - 1)
 		return -EINVAL;
 
 	ps->operand.string[ps->operand.tail++] = c;