tracing: Make sure the parsed string always terminates with '\0'

Always mark the parsed string with a terminated nul '\0' character. This removes
the need for the users to have to append the '\0' before using the parsed string.

Link: http://lkml.kernel.org/r/1516093350-12045-4-git-send-email-changbin.du@intel.com

Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Changbin Du <changbin.du@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

3 files changed, 2 insertions, 6 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 554b517c61a0..dabd9d167d42 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5015,7 +5015,6 @@ int ftrace_regex_release(struct inode *inode, struct file *file)
 
         parser = &iter->parser;
         if (trace_parser_loaded(parser)) {
-                parser->buffer[parser->idx] = 0;
                 ftrace_match_records(iter->hash, parser->buffer, parser->idx);
         }
 
@@ -5329,7 +5328,6 @@ ftrace_graph_release(struct inode *inode, struct file *file)
                 parser = &fgd->parser;
 
                 if (trace_parser_loaded((parser))) {
-                        parser->buffer[parser->idx] = 0;
                         ret = ftrace_graph_set_hash(fgd->new_hash,
                                                     parser->buffer);
                 }
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index cb90435e63da..58de825df19c 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -530,8 +530,6 @@ int trace_pid_write(struct trace_pid_list *filtered_pids,
                 ubuf += ret;
                 cnt -= ret;
 
-                parser.buffer[parser.idx] = 0;
-
                 ret = -EINVAL;
                 if (kstrtoul(parser.buffer, 0, &val))
                         break;
@@ -1268,6 +1266,8 @@ int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
         } else if (parser->idx < parser->size - 1) {
                 parser->cont = true;
                 parser->buffer[parser->idx++] = ch;
+                /* Make sure the parsed string always terminates with '\0'. */
+                parser->buffer[parser->idx] = 0;
         } else {
                 ret = -EINVAL;
                 goto out;
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 1b87157edbff..05c7172c6667 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -885,8 +885,6 @@ ftrace_event_write(struct file *file, const char __user *ubuf,
                 if (*parser.buffer == '!')
                         set = 0;
 
-                parser.buffer[parser.idx] = 0;
-
                 ret = ftrace_set_clr_event(tr, parser.buffer + !set, set);
                 if (ret)
                         goto out_put;