Re: [REGRESSION] net/ipv6/addrconf: Temporary addresses with short lifetimes generating when they shouldn't, causing applications to fail

From: Bagas Sanjaya
Date: Fri Dec 22 2023 - 08:23:09 EST


On Thu, Dec 21, 2023 at 04:10:57PM -0700, Dan Moulding wrote:
> I started running v6.7-rc5 on a desktop and began having problems
> where Chromium would frequently fail to load pages and give an
> "ERR_NETWORK_CHANGED" message instead. I also noticed instability in
> avahi-daemon (it would stop resolving local names and/or consume 100%
> CPU). Eventually I discovered that what is happening is that new
> temporary IPv6 addresses for a ULA address are being generated once
> every second, with very short preferred lifetimes (and I had an
> interface with thousands of such temporary addresses). I also found
> that it seems to be triggered when one of the devices on the network
> sends a router advertisement with a prefix that has a preferred
> lifetime of 0 (presumably it's sending that because it wants to
> deprecate that prefix).
>
> I bisected it to commit 629df6701c8a ("net: ipv6/addrconf: clamp
> preferred_lft to the minimum required"). Upon reviewing that change, I
> see that it has changed when generation of temporary addresses will be
> allowed. I believe that change might have inadvertently caused the
> kernel to violate RFC 4941 and might need to be reverted.

Can you verify that by actually reverting 629df6701c8a91 on top of net
tree?

--
An old man doll... just what I always wanted! - Clara

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