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Date: Wed, 7 Oct 2026 10:21:42 +0000
From: Dmitry Ilvokhin <d@ilvokhin.com>
To: "Jason A . Donenfeld" <Jason@zx2c4.com>
Cc: wireguard@lists.zx2c4.com
Subject: Re: [PATCH] wg-quick: darwin: fix set_dns() and del_dns() race
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On Wed, Sep 30, 2026 at 10:30:41AM +0000, Dmitry Ilvokhin wrote:
> The monitor deamon restores the DNS servers by running del_dns() from
> its INT, TERM and EXIT trap. Every route event also schedules an ALRM 2
> seconds later, and the ALRM trap runs set_dns().
> 
> If ALRM arrives during cleanup, set_dns() can run in the middle of
> del_dns(), and the DNS servers may not be restored after the WireGuard
> interface is removed.
> 
> Ignore ALRM in cleanup signal handler to avoid this race.
> 
> Signed-off-by: Dmitry Ilvokhin <d@ilvokhin.com>
> ---
> Resending the patch, since mailing list didn't accept it first time,
> because I was not a member of the list.

Hello Jason,

Any thoughts on the patch?

I applied this patch locally, tested it for a few weeks and never hit
the race again. I'd love to get the fix upstream.