[RFC 6/8] efd: avoid overflowing ring name

Stephen Hemminger
2025-12-02T17:27:08Z

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@networkplumber.org>
---
lib/efd/rte_efd.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/lib/efd/rte_efd.c b/lib/efd/rte_efd.c
index ebf1e0655f..61fd6a6646 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 +530,15 @@ rte_efd_create(const char *name, uint32_t max_num_rules, uint32_t key_len,
return NULL;
}

+ /*
+ * The name is turned into a ring name which has a limit of
+ * RTE_RING_NAMESIZE.
+ */
+ if (name == NULL || strnlen(name, RTE_RING_NAMESIZE) >= RTE_RING_NAMESIZE - sizeof(EFD_HASH_PREFIX)) {
+ EFD_LOG(ERR, "Invalid name '%s'", name);
+ return NULL;
+ }
+
/*
* Compute the minimum number of chunks (smallest power of 2)
* that can hold all of the rules
@@ -698,7 +710,13 @@ 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);
+ int cc = snprintf(ring_name, sizeof(ring_name), EFD_HASH_PREFIX "%s", table->name);
+ if (cc >= sizeof(ring_name)) {
+ EFD_LOG(ERR, "ring name '%s%s' overflow", EFD_HASH_PREFIX, table->name);
+ rte_efd_free(table);
+ return NULL;
+ }
+
/* 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