netdev - Re: [PATCH 4/6] rhashtable: allow a walk of the hash table without missing objects.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180327.114941.997071660018188736.davem@davemloft.net>
Date:   Tue, 27 Mar 2018 11:49:41 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     neilb@...e.com
Cc:     tgraf@...g.ch, herbert@...dor.apana.org.au, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/6] rhashtable: allow a walk of the hash table without
 missing objects.

From: NeilBrown <neilb@...e.com>
Date: Tue, 27 Mar 2018 10:33:04 +1100

> In many cases where the walker needs to drop out of RCU protection,
> it will take a reference to the object and this can prevent it from
> being removed from the hash table.  In those cases, the last-returned
> object can still be used as a cursor.  rhashtable cannot detect
> these cases itself.

Merely having an elevated reference count does not explicitly prevent
the object from being removed from the hash table.

This invariant might hold for the particular user of the rhashtable
instance, but it is not always the case.