linux-kernel - [tip:perf/core] tracing/function-graph: Use correct string size for snprintf

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Message-ID: <tip-d62f85d1e22e537192ce494c89540e1ac0d8bfc7@git.kernel.org>
Date:	Tue, 29 Jun 2010 09:24:00 GMT
From:	tip-bot for Chase Douglas <chase.douglas@...onical.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	rostedt@...dmis.org, chase.douglas@...onical.com,
	tglx@...utronix.de
Subject: [tip:perf/core] tracing/function-graph: Use correct string size for snprintf

Commit-ID:  d62f85d1e22e537192ce494c89540e1ac0d8bfc7
Gitweb:     http://git.kernel.org/tip/d62f85d1e22e537192ce494c89540e1ac0d8bfc7
Author:     Chase Douglas <chase.douglas@...onical.com>
AuthorDate: Tue, 15 Jun 2010 12:29:15 -0400
Committer:  Steven Rostedt <rostedt@...dmis.org>
CommitDate: Mon, 28 Jun 2010 21:11:39 -0400

tracing/function-graph: Use correct string size for snprintf

The nsecs_str string is a local variable defined as:

char nsecs_str[5];

It is possible for the snprintf call to use a size value larger than the
size of the string. This should not cause a buffer overrun as it is
written now due to the value for the string format "%03lu" can not be
larger than 1000. However, this change makes it correct. By making the
size correct we guard against potential future changes that could actually
cause a buffer overrun.

Signed-off-by: Chase Douglas <chase.douglas@...onical.com>
LKML-Reference: <1276619355-18116-1-git-send-email-chase.douglas@...onical.com>

[ added 'UL' to number 8 to fix gcc warning comparing it to sizeof() ]

Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
---
 kernel/trace/trace_functions_graph.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 79f4bac..6bff236 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -641,7 +641,8 @@ trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
 
 	/* Print nsecs (we don't want to exceed 7 numbers) */
 	if (len < 7) {
-		snprintf(nsecs_str, 8 - len, "%03lu", nsecs_rem);
+		snprintf(nsecs_str, min(sizeof(nsecs_str), 8UL - len), "%03lu",
+			 nsecs_rem);
 		ret = trace_seq_printf(s, ".%s", nsecs_str);
 		if (!ret)
 			return TRACE_TYPE_PARTIAL_LINE;
--
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