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    Subject[PATCH 5.13 536/800] bpf: Fix integer overflow in argument calculation for bpf_map_area_alloc
    Date
    From: Bui Quang Minh <minhquangbui99@gmail.com>

    [ Upstream commit 7dd5d437c258bbf4cc15b35229e5208b87b8b4e0 ]

    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
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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 aa516472ce46..3b45c23286c0 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 6f1b82b8ad49..60decd6420ca 100644
    --- 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) {
    --
    2.30.2


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