The XT_HASHLIMIT_RATE_MATCH flag mode changes the semantics of the dsthash_ent structure which represents an entry in the hashtable. There is a union area which uses a different layout to express the rate match mode. Update .checkentry path to validate the XT_HASHLIMIT_RATE_MATCH mode flag is requested by two or more different rules that refer to the same hashtable. Otherwise, uninitialized access to the burst field in the union is possible. Reject the use of the XT_HASHLIMIT_RATE_MATCH mode flag if set on by revision less than 3 too. Fixes: bea74641e378 ("netfilter: xt_hashlimit: add rate match mode") Reported-and-tested-by: Talha Berk Arslan Link: https://patch.msgid.link/20260721074629.668-1-talha.anything.info@gmail.com/ Signed-off-by: Pablo Neira Ayuso --- net/netfilter/xt_hashlimit.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c index 2704b4b60d1e..9af0fa895f73 100644 --- a/net/netfilter/xt_hashlimit.c +++ b/net/netfilter/xt_hashlimit.c @@ -117,6 +117,7 @@ struct xt_hashlimit_htable { refcount_t use; u_int8_t family; bool rnd_initialized; + bool ratematch; struct hashlimit_cfg3 cfg; /* config */ @@ -323,6 +324,7 @@ static int htable_create(struct net *net, struct hashlimit_cfg3 *cfg, kvfree(hinfo); return -ENOMEM; } + hinfo->ratematch = !!(cfg->mode & XT_HASHLIMIT_RATE_MATCH); spin_lock_init(&hinfo->lock); switch (revision) { @@ -872,7 +874,10 @@ static int hashlimit_mt_check_common(const struct xt_mtchk_param *par, } /* Check for overflow. */ - if (revision >= 3 && cfg->mode & XT_HASHLIMIT_RATE_MATCH) { + if (cfg->mode & XT_HASHLIMIT_RATE_MATCH) { + if (revision < 3) + return -EINVAL; + if (cfg->avg == 0 || cfg->avg > U32_MAX) { pr_info_ratelimited("invalid rate\n"); return -ERANGE; @@ -905,6 +910,15 @@ static int hashlimit_mt_check_common(const struct xt_mtchk_param *par, mutex_unlock(&hashlimit_mutex); return ret; } + } else { + if ((cfg->mode & XT_HASHLIMIT_RATE_MATCH && + !(*hinfo)->ratematch) || + (!(cfg->mode & XT_HASHLIMIT_RATE_MATCH) && + (*hinfo)->ratematch)) { + mutex_unlock(&hashlimit_mutex); + htable_put(*hinfo); + return -EINVAL; + } } mutex_unlock(&hashlimit_mutex); -- 2.47.3