ksym_tracer: NIL-terminate user input filter

Make sure the user input string is NULL-terminated.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: "K.Prasad" <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A52E300.7020601@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 5 deletions

diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
index 72fcb46c39c0..8cbed5a6286f 100644
--- a/kernel/trace/trace_ksym.c
+++ b/kernel/trace/trace_ksym.c
@@ -264,11 +264,7 @@ static ssize_t ksym_trace_filter_write(struct file *file,
         unsigned long ksym_addr = 0;
         int ret, op, changed = 0;
 
-        /* Ignore echo "" > ksym_trace_filter */
-        if (count == 0)
-                return 0;
-
-        input_string = kzalloc(count, GFP_KERNEL);
+        input_string = kzalloc(count + 1, GFP_KERNEL);
         if (!input_string)
                 return -ENOMEM;
 
@@ -276,6 +272,7 @@ static ssize_t ksym_trace_filter_write(struct file *file,
                 kfree(input_string);
                 return -EFAULT;
         }
+        input_string[count] = '\0';
 
         ret = op = parse_ksym_trace_str(input_string, &ksymname, &ksym_addr);
         if (ret < 0) {