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

[Vishal Moola]

On Mon, May 11, 2026 at 10:16:15AM +0800, Hongfu Li wrote:
> 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()

Just a nit, It looks like the below already have proper error handling.

> - 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;

Every malloc() call in this file has this same pattern. Maybe we'd be
better off making it a helper function?

Either way:
Reviewed-by: Vishal Moola <vishal.moola@xxxxxxxxx>