[PATCH] bpf: Fix integer overflow in argument calculation for bpf_map_area_alloc

[Bui Quang Minh]

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.

Signed-off-by: Bui Quang Minh <minhquangbu...@gmail.com>
---
 kernel/bpf/devmap.c | 4 ++--
 net/core/sock_map.c | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index f6e9c68afdd4..e849c3e8a49f 100644
--- 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 64b5ec14ff50..7a42016a981d 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -44,7 +44,7 @@ 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) {
-- 
2.17.1