linux-kernel - Re: [PATCH] virtio-console: avoid DMA from vmalloc area

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: <CAK8P3a15ykABd61Rad5iaZtGN=-+Guk0CNyCMK3XD7TgubG7hg@mail.gmail.com>
Date:   Tue, 27 Jul 2021 15:18:58 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Xianting Tian <xianting.tian@...ux.alibaba.com>
Cc:     Amit Shah <amit@...nel.org>, Arnd Bergmann <arnd@...db.de>,
        gregkh <gregkh@...uxfoundation.org>,
        Omar Sandoval <osandov@...com>,
        "open list:DRM DRIVER FOR QEMU'S CIRRUS DEVICE" 
        <virtualization@...ts.linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] virtio-console: avoid DMA from vmalloc area

On Tue, Jul 27, 2021 at 3:13 PM Xianting Tian
<xianting.tian@...ux.alibaba.com> wrote:
> @@ -1127,13 +1128,18 @@ static int put_chars(u32 vtermno, const char *buf, int count)
>         if (!port)
>                 return -EPIPE;
>
> -       data = kmemdup(buf, count, GFP_ATOMIC);
> -       if (!data)
> -               return -ENOMEM;
> +       if (is_vmalloc_addr(buf)) {
> +               data = kmemdup(buf, count, GFP_ATOMIC);

What about buffers in .data? If those are in a loadable module, I guess you have
the same problem as with vmalloc() and vmap().

is_vmalloc_or_module_addr() would take care of both, not sure if there are
other examples that don't work. In theory it could be ioremap(), kmap_atomic()
or fixmap as well, but those seem less likely to matter here.

        Arnd