Re: [PATCH nfs-utils] libnfsidmap: avoid malloc(0) for empty Local-Realms

On 5/25/26 10:51 PM, xu18736995897-9Onoh4P/[email protected] wrote:
> From: xuchenchen <xuchenchen-UOlijcLmZ/[email protected]>
> 
> conf_get_list() can return an empty list when Local-Realms is present
> but contains only empty fields, such as ", ,". In that case the Realms
> list logging path computes a buffer size of zero and then writes a NUL
> byte to the result of malloc(0).
> 
> Reserve space for the terminating NUL byte and use calloc() so the log
> buffer is valid even when the realm list is empty.
> 
> Signed-off-by: xuchenchen <xuchenchen-UOlijcLmZ/[email protected]>
Committed... (tag: nfs-utils-2-9-2-rc4)

steved
> ---
>   support/nfsidmap/libnfsidmap.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/support/nfsidmap/libnfsidmap.c b/support/nfsidmap/libnfsidmap.c
> index 0a912e52..16a79f00 100644
> --- a/support/nfsidmap/libnfsidmap.c
> +++ b/support/nfsidmap/libnfsidmap.c
> @@ -404,15 +404,14 @@ int nfs4_init_name_mapping(char *conffile)
>   	if (idmap_verbosity >= 1) {
>   		struct conf_list_node *r;
>   		char *buf = NULL;
> -		int siz=0;
> +		size_t siz = 1;
>   
>   		if (local_realms) {
>   			TAILQ_FOREACH(r, &local_realms->fields, link) {
>   				siz += (strlen(r->field)+4);
>   			}
> -			buf = malloc(siz);
> +			buf = calloc(1, siz);
>   			if (buf) {
> -				*buf = 0;
>   				TAILQ_FOREACH(r, &local_realms->fields, link) {
>   					sprintf(buf+strlen(buf), "'%s' ", r->field);
>   				}