[PATCH 4.18 078/135] Fix cg_read_strcmp()

Greg Kroah-Hartman
2018-10-16T17:13:52Z

From: Jay Kamat <jgkamat@fb.com>

[ Upstream commit 48c2bb0b9cf863e0ed78e269f188ce65b73e0fd1 ]

Fix a couple issues with cg_read_strcmp(), to improve correctness of
cgroup tests
- Fix cg_read_strcmp() always returning 0 for empty "needle" strings.
Previously, this function read to a size = 1 buffer when comparing
against empty strings, which would lead to cg_read_strcmp() comparing
two empty strings.
- Fix a memory leak in cg_read_strcmp()

Fixes: 84092dbcf901 ("selftests: cgroup: add memory controller self-tests")

Signed-off-by: Jay Kamat <jgkamat@fb.com>
Acked-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/testing/selftests/cgroup/cgroup_util.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

--- a/tools/testing/selftests/cgroup/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/cgroup_util.c
@@ -89,17 +89,28 @@ int cg_read(const char *cgroup, const ch
int cg_read_strcmp(const char *cgroup, const char *control,
const char *expected)
{
- size_t size = strlen(expected) + 1;
+ size_t size;
char *buf;
+ int ret;
+
+ /* Handle the case of comparing against empty string */
+ if (!expected)
+ size = 32;
+ else
+ size = strlen(expected) + 1;

buf = malloc(size);
if (!buf)
return -1;

- if (cg_read(cgroup, control, buf, size))
+ if (cg_read(cgroup, control, buf, size)) {
+ free(buf);
return -1;
+ }

- return strcmp(expected, buf);
+ ret = strcmp(expected, buf);
+ free(buf);
+ return ret;
}

int cg_read_strstr(const char *cgroup, const char *control, const char *needle)