2023-04-25 02:50:46

by Hao Zeng

Subject: [PATCH v2] recordmcount: Fix memory leaks in the uwrite function

Common realloc mistake: 'file_append' nulled but not freed upon failure

Signed-off-by: Hao Zeng <[email protected]>
Suggested-by: Steven Rostedt <[email protected]>
---
scripts/recordmcount.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index e30216525325..efeec898f632 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -110,6 +110,7 @@ static ssize_t uwrite(void const *const buf, size_t const count)
{
size_t cnt = count;
off_t idx = 0;
+ void *p = NULL;

file_updated = 1;

@@ -117,7 +118,13 @@ static ssize_t uwrite(void const *const buf, size_t const count)
off_t aoffset = (file_ptr + count) - file_end;

if (aoffset > file_append_size) {
- file_append = realloc(file_append, aoffset);
+ p = realloc(file_append, aoffset);
+ if (!p) {
+ free(file_append);
+ file_append = NULL;
+ } else {
+ file_append = p;
+ }
file_append_size = aoffset;
}
if (!file_append) {
--
2.37.2

2023-04-25 17:16:41

by Steven Rostedt

Subject: Re: [PATCH v2] recordmcount: Fix memory leaks in the uwrite function

On Tue, 25 Apr 2023 10:46:03 +0800
Hao Zeng <[email protected]> wrote:

> @@ -117,7 +118,13 @@ static ssize_t uwrite(void const *const buf, size_t const count)
> off_t aoffset = (file_ptr + count) - file_end;
>
> if (aoffset > file_append_size) {
> - file_append = realloc(file_append, aoffset);
> + p = realloc(file_append, aoffset);
> + if (!p) {
> + free(file_append);
> + file_append = NULL;
> + } else {
> + file_append = p;
> + }

You can simplify the above with:

if (!p)
free(file_append);

file_append = p;

-- Steve

> file_append_size = aoffset;
> }
> if (!file_append) {