[PATCH v2 3/3] tracing: make sure the parsed string always terminates with '\0'

[changbin . du]

From: Changbin Du <changbin...@intel.com>

Always mark the parsed string with a terminated '\0' even parser expects
another input to be parsed. Thus the users needn't append '0' before
using parsed string if new input is not given.

Signed-off-by: Changbin Du <changbin...@intel.com>
---
 kernel/trace/ftrace.c       | 2 --
 kernel/trace/trace.c        | 4 ++--
 kernel/trace/trace_events.c | 2 --
 3 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index ccdf366..3addb82 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5010,7 +5010,6 @@ 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);
        }
 
@@ -5324,7 +5323,6 @@ 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 b44926e..8f7fea2 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 ec0f9aa..7f8027c 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;
-- 
2.7.4