[RFC v2 10/14] efd: avoid overflowing ring name

[Bruce Richardson]

On Thu, Dec 04, 2025 at 06:28:19PM -0800, Stephen Hemminger wrote:
> The efd library allowed table name to be longer than would be
> safe when prefix was added for a ring name.
> 
> Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
> ---
>  lib/efd/rte_efd.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 

Again, not convinced that truncating is a problem here, if we document that
only N characters of the name are preserved. We can warn and continue
rather than returning error.

/Bruce

> diff --git a/lib/efd/rte_efd.c b/lib/efd/rte_efd.c
> index ebf1e0655f..b4ea8fdf33 100644
> --- a/lib/efd/rte_efd.c
> +++ b/lib/efd/rte_efd.c
> @@ -36,6 +36,9 @@ RTE_LOG_REGISTER_DEFAULT(efd_logtype, INFO);
>  #define EFD_LOG(level, ...) \
>  	RTE_LOG_LINE(level, EFD, "" __VA_ARGS__)
>  
> +/** Prefix used on ring name for hash */
> +#define EFD_HASH_PREFIX "HT_"
> +
>  #define EFD_KEY(key_idx, table) (table->keys + ((key_idx) * table->key_len))
>  /** Hash function used to determine chunk_id and bin_id for a group */
>  #define EFD_HASH(key, table) \
> @@ -527,6 +530,17 @@ rte_efd_create(const char *name, uint32_t max_num_rules, uint32_t key_len,
>  		return NULL;
>  	}
>  
> +	if (name == NULL) {
> +		EFD_LOG(ERR, "Invalid name '%s'", name);
> +		return NULL;
> +	}
> +
> +	if (snprintf(ring_name, sizeof(ring_name),
> +		     EFD_HASH_PREFIX "%s", name) >= (int)sizeof(ring_name)) {
> +		EFD_LOG(ERR, "ring name '%s%s' overflow", EFD_HASH_PREFIX, table->name);
> +		return NULL;
> +	}
> +
>  	/*
>  	 * Compute the minimum number of chunks (smallest power of 2)
>  	 * that can hold all of the rules
> @@ -698,7 +712,6 @@ rte_efd_create(const char *name, uint32_t max_num_rules, uint32_t key_len,
>  	TAILQ_INSERT_TAIL(efd_list, te, next);
>  	rte_mcfg_tailq_write_unlock();
>  
> -	snprintf(ring_name, sizeof(ring_name), "HT_%s", table->name);
>  	/* Create ring (Dummy slot index is not enqueued) */
>  	r = rte_ring_create(ring_name, rte_align32pow2(table->max_num_rules),
>  			offline_cpu_socket, 0);
> -- 
> 2.51.0
>