linux-kernel - Re: [PATCH v2 1/2] nvme: Fix compat NVME_IOCTL_SUBMIT

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: <20200328082601.GA7658@infradead.org>
Date:   Sat, 28 Mar 2020 01:26:01 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Nick Bowler <nbowler@...conx.ca>
Cc:     linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Sagi Grimberg <sagi@...mberg.me>,
        Christoph Hellwig <hch@...radead.org>,
        Keith Busch <kbusch@...nel.org>
Subject: Re: [PATCH v2 1/2] nvme: Fix compat NVME_IOCTL_SUBMIT_IO numbering

On Sat, Mar 28, 2020 at 01:09:08AM -0400, Nick Bowler wrote:
> When __u64 has 64-bit alignment, the nvme_user_io structure has trailing
> padding.  This causes problems in the compat case with 32-bit userspace
> that has less strict alignment because the size of the structure differs.
> 
> Since the NVME_IOCTL_SUBMIT_IO macro encodes the structure size itself,
> the result is that this ioctl does not work at all in such a scenario:
> 
>   # nvme read /dev/nvme0n1 -z 512
>   submit-io: Inappropriate ioctl for device
> 
> But by the same token, this makes it easy to handle both cases and
> since the structures differ only in unused trailing padding bytes
> we can simply not read those bytes.
> 
> Signed-off-by: Nick Bowler <nbowler@...conx.ca>

I think we already have a similar patch titled
"nvme: Add compat_ioctl handler for NVME_IOCTL_SUBMIT_IO" in
linux-next, with the difference of actually implementing the
.compat_ioctl entry point.