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From:   David Howells <dhowells@redhat.com>
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To:     Herbert Xu <herbert@gondor.apana.org.au>
Cc:     dhowells@redhat.com,
        syzbot <syzbot+f2c120b449b209d89efa@syzkaller.appspotmail.com>,
        davem@davemloft.net, linux-crypto@vger.kernel.org,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [crypto?] WARNING in extract_iter_to_sg
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Date:   Thu, 06 Jul 2023 00:06:02 +0100
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> CPU: 0 PID: 26699 Comm: syz-executor.2 Not tainted 6.4.0-rc7-syzkaller-0=
1944-g3674fbf0451d #0

Looking at the version string, this is from net-next before the merger wit=
h
Linus's tree after the point where Linus had merged:

https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/log/=
?h=3Dfor-6.5/splice

> extract_iter_to_sg(3) unsupported

This is ITER_PIPE (type 3) before is removed by:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/=
?id=3D3fc40265ae2b48a7475c41c5c0b256374c419f4b

=46rom that point on ITER_XARRAY is type 3 and there's a case for that in
extract_iter_to_sg().

So the fix for this is to merge it with the splice tree - which Linus has
already done, so this should be fixed upstream.

With hindsight, I should've used iov_iter_get_pages*() rather than
iov_iter_extract_pages() and extract_iter_to_sg() in the networking code
recvmsg() path until after the merge.

David