netdev - Re: [Patch net-next v2] net: fix dev_ifsioc

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]

Date:   Mon, 1 Feb 2021 21:27:33 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Cong Wang <cong.wang@...edance.com>,
        "Gong, Sishuai" <sishuai@...due.edu>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [Patch net-next v2] net: fix dev_ifsioc_locked() race condition

On Mon, Feb 1, 2021 at 7:40 PM Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Sat, 30 Jan 2021 18:27:55 -0800 Cong Wang wrote:
> > From: Cong Wang <cong.wang@...edance.com>
> >
> > dev_ifsioc_locked() is called with only RCU read lock, so when
> > there is a parallel writer changing the mac address, it could
> > get a partially updated mac address, as shown below:
> >
> > Thread 1                      Thread 2
> > // eth_commit_mac_addr_change()
> > memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
> >                               // dev_ifsioc_locked()
> >                               memcpy(ifr->ifr_hwaddr.sa_data,
> >                                       dev->dev_addr,...);
> >
> > Close this race condition by guarding them with a RW semaphore,
> > like netdev_get_name(). The writers take RTNL anyway, so this
> > will not affect the slow path. To avoid bothering existing
> > dev_set_mac_address() callers in drivers, introduce a new wrapper
> > just for user-facing callers in ioctl and rtnetlink.
>
> Some of the drivers need to be update, tho, right? At a quick look at
> least bond and tun seem to be making calls to dev_set_mac_address()
> on IOCTL paths.

Ah, good catch! Clearly I missed those special IOCTL's.

Thanks,