[PATCH 41/87] trace-cmd library: Fix possible memory leak in read_ftrace_printk()

["Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>]

Some error paths in read_ftrace_printk() may lead to a memory leak.
Improved the error handling of this internal function to avoid it.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 lib/trace-cmd/trace-input.c | 33 +++++++++++++++++++--------------
 1 file changed, 19 insertions(+), 14 deletions(-)

diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 14052a11..5eaf030e 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -888,7 +888,8 @@ out:
 static int read_ftrace_printk(struct tracecmd_input *handle)
 {
 	unsigned int size;
-	char *buf;
+	char *buf = NULL;
+	int ret;
 
 	if (CHECK_READ_STATE(handle, TRACECMD_FILE_PRINTK))
 		return 0;
@@ -897,29 +898,33 @@ static int read_ftrace_printk(struct tracecmd_input *handle)
 		add_section(handle, TRACECMD_OPTION_PRINTK, 0, 0,
 			    lseek64(handle->fd, 0, SEEK_CUR));
 
-
-	if (read4(handle, &size) < 0)
-		return -1;
-	if (!size)
-		return 0; /* OK? */
+	ret = read4(handle, &size);
+	if (ret < 0)
+		goto out;
+	if (!size) {
+		handle->file_state = TRACECMD_FILE_PRINTK;
+		goto out; /* OK? */
+	}
 
 	buf = malloc(size + 1);
-	if (!buf)
-		return -1;
-	if (do_read_check(handle, buf, size)) {
-		free(buf);
-		return -1;
+	if (!buf) {
+		ret = -1;
+		goto out;
 	}
+	ret = do_read_check(handle, buf, size);
+	if (ret < 0)
+		goto out;
 
 	buf[size] = 0;
 
 	tep_parse_printk_formats(handle->pevent, buf);
 
-	free(buf);
-
 	handle->file_state = TRACECMD_FILE_PRINTK;
+	ret = 0;
 
-	return 0;
+out:
+	free(buf);
+	return ret;
 }
 
 static int read_and_parse_cmdlines(struct tracecmd_input *handle);
-- 
2.31.1