bpf: Fix integer overflow in argument calculation for bpf_map_area_alloc

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: 0d2c4f964050 ("bpf: Eliminate rlimit-based memory accounting for sockmap and sockhash maps")
Fixes: 99c51064fb06 ("devmap: Use bpf_map_area_alloc() for allocating hash buckets")
Fixes: 546ac1ffb70d ("bpf: add devmap, a map for storing net device references")
Signed-off-by: Bui Quang Minh <minhquangbui99@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210613143440.71975-1-minhquangbui99@gmail.com

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index aa51647..3b45c23 100644 (file)
--- a/kernel/bpf/devmap.c
+++ b/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]);
@@ -143,7 +143,7 @@ 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)

diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index 6f1b82b..60decd6 100644 (file)
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -48,7 +48,7 @@ static struct bpf_map *sock_map_alloc(union bpf_attr *attr)
        bpf_map_init_from_attr(&stab->map, attr);
        raw_spin_lock_init(&stab->lock);
 
-       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) {