linux-kernel - [PATCH 1/4] tracing: fix a typo in tracing_cpumask

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Message-ID: <4A35B86A.7070608@cn.fujitsu.com>
Date:	Mon, 15 Jun 2009 10:56:42 +0800
From:	Li Zefan <lizf@...fujitsu.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/4] tracing: fix a typo in tracing_cpumask_write()

It's tracing_cpumask_new that should be kfree()ed.

This causes tracing_cpumask to be freed due to the typo:

 # echo z > tracing_cpumask
 bash: echo: write error: Invalid argument

And subsequent reads/writes to tracing_cpuamsk will access this
already-freed tracing_cpumask, thus may lead to crash.

[ Impact: fix leak and crash when writing invalid val to tracing_cpumask ]

Signed-off-by: Li Zefan <lizf@...fujitsu.com>
---
 kernel/trace/trace.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8acd9b8..7355a38 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2191,11 +2191,12 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf,
 	if (!alloc_cpumask_var(&tracing_cpumask_new, GFP_KERNEL))
 		return -ENOMEM;
 
-	mutex_lock(&tracing_cpumask_update_lock);
 	err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
 	if (err)
 		goto err_unlock;
 
+	mutex_lock(&tracing_cpumask_update_lock);
+
 	local_irq_disable();
 	__raw_spin_lock(&ftrace_max_lock);
 	for_each_tracing_cpu(cpu) {
@@ -2223,8 +2224,7 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf,
 	return count;
 
 err_unlock:
-	mutex_unlock(&tracing_cpumask_update_lock);
-	free_cpumask_var(tracing_cpumask);
+	free_cpumask_var(tracing_cpumask_new);
 
 	return err;
 }
-- 
1.5.4.rc3

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