Re: [syzbot] [batman?] BUG: soft lockup in sys_sendmsg

Sven Eckelmann
2024-02-12T11:32:04Z

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On Monday, 12 February 2024 11:41:38 CET Eric Dumazet wrote:
> This patch [1] looks suspicious

Shouldn't be caused by this - but this might be another way to trigger the
problem. The problem would be visible even without it when a mtu is explicitly
set. But the reproducer is not available so I can't actually check what is
going on.

> I think batman-adv should reject too small MTU values.

You are refering to the size calculated by
batadv_tt_local_table_transmit_size(), right? And yes, I would agree that it
looks suspicious and might not have been correctly integrated in
batadv_max_header_len() when commit a19d3d85e1b8 ("batman-adv: limit local
translation table max size") introduced the code. But I think we also need to
remove interfaces again when receiving NETDEV_CHANGEMTU and an interface is
not having the correctly sized anymore. So have to check how to do this the
best way.

Kind regards,
Sven

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