bpf: Fix integer overflow in argument calculation for bpf_map_area_alloc

stable inclusion
from stable-v5.10.87
commit 613725436e69fc3ccdf39f827bb274f999288dba
bugzilla: 186049 https://gitee.com/openeuler/kernel/issues/I4QVYL

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=613725436e69fc3ccdf39f827bb274f999288dba

--------------------------------

commit 7dd5d437 upstream.

In 32-bit architecture, the result of sizeof() is a 32-bit integer so
the expression becomes the multiplication between 2 32-bit integer which
can potentially leads to integer overflow. As a result,
bpf_map_area_alloc() allocates less memory than needed.

Fix this by casting 1 operand to u64.

Fixes: 0d2c4f96 ("bpf: Eliminate rlimit-based memory accounting for sockmap and sockhash maps")
Fixes: 99c51064 ("devmap: Use bpf_map_area_alloc() for allocating hash buckets")
Fixes: 546ac1ff ("bpf: add devmap, a map for storing net device references")
Signed-off-by: NBui Quang Minh <minhquangbui99@gmail.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210613143440.71975-1-minhquangbui99@gmail.comSigned-off-by: NConnor O'Brien <connoro@google.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

kernel/bpf/devmap.c

@@ -92,7 +92,7 @@ static struct hlist_head *dev_map_create_hash(unsigned int entries,
 	int i;
 	struct hlist_head *hash;
 
-	hash = bpf_map_area_alloc(entries * sizeof(*hash), numa_node);
+	hash = bpf_map_area_alloc((u64) entries * sizeof(*hash), numa_node);
 	if (hash != NULL)
 		for (i = 0; i < entries; i++)
 			INIT_HLIST_HEAD(&hash[i]);
@@ -153,7 +153,7 @@ static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
 
 		spin_lock_init(&dtab->index_lock);
 	} else {
-		dtab->netdev_map = bpf_map_area_alloc(dtab->map.max_entries *
+		dtab->netdev_map = bpf_map_area_alloc((u64) dtab->map.max_entries *
 						      sizeof(struct bpf_dtab_netdev *),
 						      dtab->map.numa_node);
 		if (!dtab->netdev_map)

net/core/sock_map.c

@@ -52,7 +52,7 @@ static struct bpf_map *sock_map_alloc(union bpf_attr *attr)
 	if (err)
 		goto free_stab;
 
-	stab->sks = bpf_map_area_alloc(stab->map.max_entries *
+	stab->sks = bpf_map_area_alloc((u64) stab->map.max_entries *
 				       sizeof(struct sock *),
 				       stab->map.numa_node);
 	if (stab->sks)