From: David Howells <dhowells@redhat.com>
To: Eric Dumazet <edumazet@google.com>
Cc: dhowells@redhat.com,
syzbot <syzbot+62cbf263225ae13ff153@syzkaller.appspotmail.com>,
bpf@vger.kernel.org, davem@davemloft.net, dsahern@kernel.org,
kuba@kernel.org, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org, pabeni@redhat.com,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [net?] WARNING in __ip6_append_data
Date: Mon, 18 Sep 2023 11:03:02 +0100 [thread overview]
Message-ID: <3905046.1695031382@warthog.procyon.org.uk> (raw)
In-Reply-To: <3793723.1694795079@warthog.procyon.org.uk>
David Howells <dhowells@redhat.com> wrote:
> I think the attached is probably an equivalent cleaned up reproducer. Note
> that if the length given to sendfile() is less than 65536, it fails with
> EINVAL before it gets into __ip6_append_data().
Actually, it only fails with EINVAL if the size is not a multiple of the block
size of the source file because it's open O_DIRECT so, say, 65536-512 is fine
(and works).
But thinking more on this further, is this even a bug in my code, I wonder?
The length passed is 65536 - but a UDP packet can't carry that, so it
shouldn't it have errored out before getting that far? (which is what it
seems to do when I try it).
I don't see how we get past the length check in ip6_append_data() with the
reproducer we're given unless the MTU is somewhat bigger than 65536 (is that
even possible?)
David
next prev parent reply other threads:[~2023-09-18 10:03 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-13 6:19 [syzbot] [net?] WARNING in __ip6_append_data syzbot
2023-09-13 8:41 ` Eric Dumazet
2023-09-15 15:32 ` David Howells
2023-09-15 16:24 ` David Howells
2023-09-18 10:03 ` David Howells [this message]
2023-09-18 13:58 ` Willem de Bruijn
2023-09-18 14:04 ` Eric Dumazet
2023-09-19 8:27 ` Tom Parkin
2023-09-19 9:04 ` Eric Dumazet
2023-09-18 14:46 ` David Howells
2023-09-18 10:11 ` David Howells
2023-09-18 10:33 ` syzbot
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