[PATCH] selftests/cgroup: check malloc return value in alloc_anon functions

[Hongfu Li]

The alloc_anon() function calls malloc() without checking for a NULL
return. If memory allocation fails, a NULL pointer dereference will
occur when accessing the buffer.

Add proper error handling to return -1 when malloc() fails in all
four alloc_anon variants:
- alloc_anon()
- alloc_anon_50M_check()
- alloc_anon_noexit()
- alloc_anon_50M_check_swap()

Signed-off-by: Hongfu Li <lihongfu@xxxxxxxxxx>
---
 tools/testing/selftests/cgroup/test_memcontrol.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index b43da9bc20c4..8ef9c99a82eb 100644
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -61,6 +61,11 @@ int alloc_anon(const char *cgroup, void *arg)
 	char *buf, *ptr;
 
 	buf = malloc(size);
+	if (buf == NULL) {
+		fprintf(stderr, "malloc() failed\n");
+		return -1;
+	}
+
 	for (ptr = buf; ptr < buf + size; ptr += PAGE_SIZE)
 		*ptr = 0;
 
-- 
2.25.1