From: Al Viro <viro@ZenIV•linux.org.uk>
To: Cong Wang <xiyou.wangcong@gmail•com>
Cc: netdev@vger•kernel.org, shankarapailoor@gmail•com,
Tetsuo Handa <penguin-kernel@i-love•sakura.ne.jp>,
Lorenzo Colitti <lorenzo@google•com>
Subject: Re: [Patch net] socket: close race condition between sock_close() and sockfs_setattr()
Date: Thu, 7 Jun 2018 22:26:31 +0100 [thread overview]
Message-ID: <20180607212631.GW30522@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20180607203949.16945-1-xiyou.wangcong@gmail.com>
On Thu, Jun 07, 2018 at 01:39:49PM -0700, Cong Wang wrote:
> fchownat() doesn't even hold refcnt of fd until it figures out
> fd is really needed (otherwise is ignored) and releases it after
> it resolves the path. This means sock_close() could race with
> sockfs_setattr(), which leads to a NULL pointer dereference
> since typically we set sock->sk to NULL in ->release().
>
> As pointed out by Al, this is unique to sockfs. So we can fix this
> in socket layer by acquiring inode_lock in sock_close() and
> checking against NULL in sockfs_setattr().
That looks like a massive overkill - it's way heavier than it should be.
And it's very likely to trigger shitloads of deadlock warnings, some
possibly even true.
next prev parent reply other threads:[~2018-06-07 21:26 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-07 20:39 [Patch net] socket: close race condition between sock_close() and sockfs_setattr() Cong Wang
2018-06-07 21:26 ` Al Viro [this message]
2018-06-07 21:45 ` Cong Wang
2018-06-07 22:04 ` Al Viro
2018-06-07 22:15 ` Cong Wang
2018-06-07 22:32 ` Al Viro
2018-06-10 19:27 ` David Miller
2018-06-10 19:43 ` Cong Wang
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