linux-kernel - Re: security issue: data exposure when using block layer secure erase

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Message-ID: <20220318091054.GA31758@lst.de>
Date:   Fri, 18 Mar 2022 10:10:54 +0100
From:   Christoph Hellwig <hch@....de>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     Christoph Hellwig <hch@....de>, axboe@...nel.dk,
        jaegeuk@...nel.org, chao@...nel.org, ulf.hansson@...aro.org,
        Adrian Hunter <adrian.hunter@...el.com>,
        Daeho Jeong <daehojeong@...gle.com>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mmc@...r.kernel.org
Subject: Re: security issue: data exposure when using block layer secure
 erase

On Wed, Mar 16, 2022 at 06:05:29PM +0000, Eric Biggers wrote:
> __blkdev_issue_discard() can break up the region into multiple bios, but I don't
> see where it actually skips parts of the region.  Can you explain more
> specifically where the problem is?

You're right.  We used to skip misaligned parts, but that was actually
fixed two years ago.