netfilter: conntrack: clamp maximum hashtable size to INT_MAX

BugLink: https://bugs.launchpad.net/bugs/2106770

[ Upstream commit b541ba7 ]

Use INT_MAX as maximum size for the conntrack hashtable. Otherwise, it
is possible to hit WARN_ON_ONCE in __kvmalloc_node_noprof() when
resizing hashtable because __GFP_NOWARN is unset. See:

  0708a0a ("mm: Consider __GFP_NOWARN flag for oversized kvmalloc() calls")

Note: hashtable resize is only possible from init_netns.

Fixes: 9cc1c73 ("netfilter: conntrack: avoid integer overflow when resizing")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
CVE-2025-21648
Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com>
Signed-off-by: Mehmet Basaran <mehmet.basaran@canonical.com>

Author: ummakynes

net/netfilter/nf_conntrack_core.c

@@ -2558,12 +2558,15 @@ void *nf_ct_alloc_hashtable(unsigned int *sizep, int nulls)
 	struct hlist_nulls_head *hash;
 	unsigned int nr_slots, i;
 
-	if (*sizep > (UINT_MAX / sizeof(struct hlist_nulls_head)))
+	if (*sizep > (INT_MAX / sizeof(struct hlist_nulls_head)))
 		return NULL;
 
 	BUILD_BUG_ON(sizeof(struct hlist_nulls_head) != sizeof(struct hlist_head));
 	nr_slots = *sizep = roundup(*sizep, PAGE_SIZE / sizeof(struct hlist_nulls_head));
 
+	if (nr_slots > (INT_MAX / sizeof(struct hlist_nulls_head)))
+		return NULL;
+
 	hash = kvcalloc(nr_slots, sizeof(struct hlist_nulls_head), GFP_KERNEL);
 
 	if (hash && nulls)