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From: James Chapman <jchapman@katalix.com>
To: bpf@vger.kernel.org, kafai@fb.com
Cc: netdev@vger.kernel.org
Subject: bpf's usage of sk_user_data
Date: Tue, 7 Jul 2020 10:37:30 +0100	[thread overview]
Message-ID: <20200707093730.GC21324@katalix.com> (raw)

I'm investigating a crash found by syzbot which turns out to be caused
by bpf_sk_reuseport_detach assuming ownership of sk_user_data in the
UDP socket destroy path and corrupts metadata of a UDP socket user (l2tp).

Here's the syzbot report:
https://syzkaller.appspot.com/bug?extid=9f092552ba9a5efca5df

I submitted a patch to l2tp to workaround this by having l2tp refuse
to use a UDP socket with SO_REUSEPORT set. But this isn't the right
fix. Can BPF be changed to store its metadata elsewhere such that
other socket users which use sk_user_data can co-exist with BPF?

The email thread discussing this is at:
https://lore.kernel.org/netdev/20200706.124536.774178117550894539.davem@davemloft.net/


             reply	other threads:[~2020-07-07  9:37 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-07  9:37 James Chapman [this message]
2020-07-07 18:32 ` bpf's usage of sk_user_data Martin KaFai Lau

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