Re: [PATCH v3] libsepol: policydb_read(): use a static string for policydb_str

[Rahul Sandhu <nvraxn@posteo.uk>]

Ping

On Fri Apr 03, 2026 at 07:56 AM BST, Rahul Sandhu wrote:
> We know the maximum possible size of policydb_str at compile time; it's
> POLICYDB_STRING_MAX_LENGTH + 1 (with + 1 accounting for the null term).
> As POLICYDB_STRING_MAX_LENGTH is trivially small, make it a static str,
> avoiding an extra allocation.
>
> Signed-off-by: Rahul Sandhu <nvraxn@posteo.uk>
> ---
>  libsepol/src/policydb.c | 15 +--------------
>  1 file changed, 1 insertion(+), 14 deletions(-)
>
> v3: fix authorship mess
>
> diff --git a/libsepol/src/policydb.c b/libsepol/src/policydb.c
> index 9760b164..8d290d86 100644
> --- a/libsepol/src/policydb.c
> +++ b/libsepol/src/policydb.c
> @@ -4192,7 +4192,7 @@ int policydb_read(policydb_t * p, struct policy_file *fp, unsigned verbose)
>  	unsigned int i, j, r_policyvers;
>  	uint32_t buf[5], nprim;
>  	size_t len, nel;
> -	char *policydb_str;
> +	char policydb_str[POLICYDB_STRING_MAX_LENGTH + 1];
>  	const struct policydb_compat_info *info;
>  	unsigned int policy_type, bufindex;
>  	ebitmap_node_t *tnode;
> @@ -4222,16 +4222,9 @@ int policydb_read(policydb_t * p, struct policy_file *fp, unsigned verbose)
>  		return POLICYDB_ERROR;
>  	}
>  
> -	policydb_str = malloc(len + 1);
> -	if (!policydb_str) {
> -		ERR(fp->handle, "unable to allocate memory for policydb "
> -		    "string of length %zu", len);
> -		return POLICYDB_ERROR;
> -	}
>  	rc = next_entry(policydb_str, fp, len);
>  	if (rc < 0) {
>  		ERR(fp->handle, "truncated policydb string identifier");
> -		free(policydb_str);
>  		return POLICYDB_ERROR;
>  	}
>  	policydb_str[len] = 0;
> @@ -4248,22 +4241,16 @@ int policydb_read(policydb_t * p, struct policy_file *fp, unsigned verbose)
>  		if (i == POLICYDB_TARGET_SZ) {
>  			ERR(fp->handle, "cannot find a valid target for policy "
>  				"string %s", policydb_str);
> -			free(policydb_str);
>  			return POLICYDB_ERROR;
>  		}
>  	} else {
>  		if (strcmp(policydb_str, POLICYDB_MOD_STRING)) {
>  			ERR(fp->handle, "invalid string identifier %s",
>  				policydb_str);
> -			free(policydb_str);
>  			return POLICYDB_ERROR;
>  		}
>  	}
>  
> -	/* Done with policydb_str. */
> -	free(policydb_str);
> -	policydb_str = NULL;
> -
>  	/* Read the version, config, and table sizes (and policy type if it's a module). */
>  	if (policy_type == POLICY_KERN)
>  		nel = 4;

-- 
Rahul Sandhu