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From: Greg KH <gregkh@linuxfoundation.org>
To: Stan Hu <stanhu@gmail.com>
Cc: stable@vger.kernel.org, Miklos Szeredi <mszeredi@redhat.com>
Subject: Re: Request for cherry-picking overlayfs fixes in 5.10.x stable
Date: Fri, 3 Dec 2021 11:31:04 +0100	[thread overview]
Message-ID: <Yanx6KobwiQoBQfU@kroah.com> (raw)
In-Reply-To: <CAMBWrQ=1MKxnMT_6Jnqp_xxr7psVywPBJc6p1qCy9ENY8RF2Qw@mail.gmail.com>

On Thu, Dec 02, 2021 at 04:29:34PM -0800, Stan Hu wrote:
> A number of users have reported that under certain conditions using
> the overlay filesystem, copy_file_range() can unexpectedly create a
> 0-byte file. [0]
> 
> This bug can cause significant problems because applications that copy
> files expect the target file to match the source immediately after the
> copy. After upgrading from Linux 5.4 to Linux 5.10, our Docker-based
> CI tests started failing due to this bug, since Ruby's IO.copy_stream
> uses this system call. We have worked around the problem by touching
> the target file before using it, but this shouldn't be necessary.
> Other projects, such as Rust, have added similar workarounds. [1]
> 
> As discussed in the linux-fsdevel mailing list [2], the bug appears to
> be present in Linux 5.6 to 5.10, but not in Linux 5.11. We should be
> able to cherry-pick the following upstream patches to fix this. Could
> you cherry-pick them to 5.10.x stable? I've confirmed that these
> patches, applied from top to bottom to that branch, pass the
> reproduction test [3]:
> 
> 82a763e61e2b601309d696d4fa514c77d64ee1be
> 9b91b6b019fda817eb52f728eb9c79b3579760bc
> 
> The diffstat:
> 
>  fs/overlayfs/file.c | 59
> +++++++++++++++++++++++++++++++----------------------------
>  1 file changed, 31 insertions(+), 28 deletions(-)
> 
> Note that these patches do not pick cleanly into 5.6.x - 5.9.x stable.
> 
> [0] https://github.com/docker/for-linux/issues/1015
> [1] https://github.com/rust-lang/rust/blob/342db70ae4ecc3cd17e4fa6497f0a8d9534ccfeb/library/std/src/sys/unix/kernel_copy.rs#L565-L569
> [2] https://marc.info/?l=linux-fsdevel&m=163847383311699&w=2
> [3] https://github.com/docker/for-linux/issues/1015#issuecomment-841915668

Now queued up, thanks,

greg k-h


      reply	other threads:[~2021-12-03 10:31 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-03  0:29 Request for cherry-picking overlayfs fixes in 5.10.x stable Stan Hu
2021-12-03 10:31 ` Greg KH [this message]

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