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Date: Tue, 3 Feb 2026 17:32:36 +0100
From: Christoph Hellwig <hch@lst.de>
To: Askar Safin <safinaskar@gmail.com>
Cc: dhowells@redhat.com, axboe@kernel.dk, brauner@kernel.org,
	cem@kernel.org, djwong@kernel.org, hch@lst.de,
	kundan.kumar@samsung.com, linux-block@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
	viro@zeniv.linux.org.uk, willy@infradead.org, wqu@suse.com
Subject: Re: [PATCH 03/14] iov_iter: extract a iov_iter_extract_bvecs
 helper from bio code
Message-ID: <20260203163236.GA28989@lst.de>
References: <1763225.1769180226@warthog.procyon.org.uk> <20260203102821.3017412-1-safinaskar@gmail.com>
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On Tue, Feb 03, 2026 at 01:28:21PM +0300, Askar Safin wrote:
> David Howells <dhowells@redhat.com>:
> > Can we make vmsplice() just copy data?
> 
> vmsplice already caused at least one security issue in the past:
> CVE-2020-29374 (see https://lwn.net/Articles/849638/ ). There may be other
> CVEs, try to search CVE database.
> 
> Also, I think vmsplice is rarely used.
> 
> So, if you author a patch, which makes vmsplice equivalent to readv/writev,
> and mention these CVEs, then, I think, such patch has high chance to
> succeed.

I'd be all for killing it, especially as getting it to properly pin
the user buffers is still unsolved so far.