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    Subject[PATCH 6.0 295/862] bpf: Ensure correct locking around vulnerable function find_vpid()
    Date
    From: Lee Jones <lee@kernel.org>

    [ Upstream commit 83c10cc362d91c0d8d25e60779ee52fdbbf3894d ]

    The documentation for find_vpid() clearly states:

    "Must be called with the tasklist_lock or rcu_read_lock() held."

    Presently we do neither for find_vpid() instance in bpf_task_fd_query().
    Add proper rcu_read_lock/unlock() to fix the issue.

    Fixes: 41bdc4b40ed6f ("bpf: introduce bpf subcommand BPF_TASK_FD_QUERY")
    Signed-off-by: Lee Jones <lee@kernel.org>
    Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
    Acked-by: Yonghong Song <yhs@fb.com>
    Link: https://lore.kernel.org/bpf/20220912133855.1218900-1-lee@kernel.org
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    kernel/bpf/syscall.c | 2 ++
    1 file changed, 2 insertions(+)

    diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
    index f798acd43a28..22e7a805c672 100644
    --- a/kernel/bpf/syscall.c
    +++ b/kernel/bpf/syscall.c
    @@ -4395,7 +4395,9 @@ static int bpf_task_fd_query(const union bpf_attr *attr,
    if (attr->task_fd_query.flags != 0)
    return -EINVAL;

    + rcu_read_lock();
    task = get_pid_task(find_vpid(pid), PIDTYPE_PID);
    + rcu_read_unlock();
    if (!task)
    return -ENOENT;

    --
    2.35.1


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