netdev - Re: [PATCH net] net: sched: flower: insert new filter to idr after setting its mask

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] [day] [month] [year] [list]

Message-Id: <20190306.105346.2043508562178833304.davem@davemloft.net>
Date:   Wed, 06 Mar 2019 10:53:46 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     vladbu@...lanox.com
Cc:     netdev@...r.kernel.org, jhs@...atatu.com, xiyou.wangcong@...il.com,
        jiri@...nulli.us, roid@...lanox.com
Subject: Re: [PATCH net] net: sched: flower: insert new filter to idr after
 setting its mask

From: Vlad Buslov <vladbu@...lanox.com>
Date: Wed,  6 Mar 2019 16:22:12 +0200

> When adding new filter to flower classifier, fl_change() inserts it to
> handle_idr before initializing filter extensions and assigning it a mask.
> Normally this ordering doesn't matter because all flower classifier ops
> callbacks assume rtnl lock protection. However, when filter has an action
> that doesn't have its kernel module loaded, rtnl lock is released before
> call to request_module(). During this time the filter can be accessed bu
> concurrent task before its initialization is completed, which can lead to a
> crash.
> 
> Example case of NULL pointer dereference in concurrent dump:
 ...
> Extension initialization and mask assignment don't depend on fnew->handle
> that is allocated by idr_alloc_u32(). Move idr allocation code after action
> creation and mask assignment in fl_change() to prevent concurrent access
> to not fully initialized filter when rtnl lock is released to load action
> module.
> 
> Fixes: 01683a146999 ("net: sched: refactor flower walk to iterate over idr")
> Signed-off-by: Vlad Buslov <vladbu@...lanox.com>
> Reviewed-by: Roi Dayan <roid@...lanox.com>

Applied and queued up for -stable.