linux-kernel - Re: [PATCH] block: increment diskseq on all media change events

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Date:   Tue, 20 Jun 2023 07:18:20 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Demi Marie Obenour <demi@...isiblethingslab.com>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        Christoph Hellwig <hch@...radead.org>, stable@...r.kernel.org
Subject: Re: [PATCH] block: increment diskseq on all media change events


On Wed, 07 Jun 2023 13:08:37 -0400, Demi Marie Obenour wrote:
> Currently, associating a loop device with a different file descriptor
> does not increment its diskseq.  This allows the following race
> condition:
> 
> 1. Program X opens a loop device
> 2. Program X gets the diskseq of the loop device.
> 3. Program X associates a file with the loop device.
> 4. Program X passes the loop device major, minor, and diskseq to
>    something.
> 5. Program X exits.
> 6. Program Y detaches the file from the loop device.
> 7. Program Y attaches a different file to the loop device.
> 8. The opener finally gets around to opening the loop device and checks
>    that the diskseq is what it expects it to be.  Even though the
>    diskseq is the expected value, the result is that the opener is
>    accessing the wrong file.
> 
> [...]

Applied, thanks!

[1/1] block: increment diskseq on all media change events
      commit: b90ecc0379eb7bbe79337b0c7289390a98752646

Best regards,
-- 
Jens Axboe