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 ]

Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A35B86A.7070608@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8acd9b81a5d..7355a38e18b 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;
 }