From mboxrd@z Thu Jan  1 00:00:00 1970
From: Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH bpf-next v10 06/10] bpf,landlock: Add a new map type:
 inode
Date: Sun, 8 Sep 2019 23:19:54 +0100
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To: =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= <mic@digikod.net>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>, =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= <mickael.salaun@ssi.gouv.fr>, linux-kernel@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>, Andrew Morton <akpm@linux-foundation.org>, Andy Lutomirski <luto@amacapital.net>, Arnaldo Carvalho de Melo <acme@kernel.org>, Casey Schaufler <casey@schaufler-ca.com>, Daniel Borkmann <daniel@iogearbox.net>, David Drysdale <drysdale@google.com>, "David S . Miller" <davem@davemloft.net>, "Eric W . Biederman" <ebiederm@xmission.com>, James Morris <jmorris@namei.org>, Jann Horn <jann@thejh.net>, John Johansen <john.johansen@canonical.com>, Jonathan Corbet <corbet@lwn.net>, Kees Cook <keescook@chromium.org>, Michael Kerrisk <mtk.manpages@gmail.com>, Paul Moore <paul@paul-moore.com>
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On Mon, Sep 09, 2019 at 12:09:57AM +0200, Mickaël Salaün wrote:

> >>> +    rcu_read_lock();
> >>> +    ptr = htab_map_lookup_elem(map, &inode);
> >>> +    iput(inode);

Wait a sec.  You are doing _what_ under rcu_read_lock()?

> >>> +    if (IS_ERR(ptr)) {
> >>> +            ret = PTR_ERR(ptr);
> >>> +    } else if (!ptr) {
> >>> +            ret = -ENOENT;
> >>> +    } else {
> >>> +            ret = 0;
> >>> +            copy_map_value(map, value, ptr);
> >>> +    }
> >>> +    rcu_read_unlock();