From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5474838C2D0; Tue, 18 Aug 2026 07:41:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787038908; cv=none; b=MJ61CYhiYVTJhhBfrZvBO4FfbgM7gxed+e2cPPuc7ncn441RxDYuFpRSEsnqSvLZ6Q5mqK6XltRMQJ9cUH4V4bKaXzShci5Bd/nQ3NT+DwpvdugzVa0dC2a4+aG/epyuBY+IY9/KzjX6J+dGZtx08OOqeFm8n9a16F17XxxGzLw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787038908; c=relaxed/simple; bh=WJLrsvW1KgVUoORHlEfWwIngWQzHXJzyHjRUcNkbe4s=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=UPKcIBXt14veOm3wevhjBskOxw0jeC5gnqQgjFNsUCYYAzllYGig3SdKZFAzBfqTNsaEA3aKEqQbMTmo9GwlRkHXdXuo+EqAqaLeN/TBvahLA0LRZDTeZlZaovMMjkdhdPdEHg8K5CypD7L+hmDNda8bJlCWCIpvXEzcrbgv1mU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QqqJk8XT; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="QqqJk8XT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2F7E81F000E9; Tue, 18 Aug 2026 07:41:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787038907; bh=ekUkHjTKM0gbzEISO/sz6tlY6bNtVcf9G+2Ep4ZlXcA=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=QqqJk8XTMs/r9JUA8w+ttb8o7C8EeUSBl9heAbvqWAtyvt4d+nF4rEnjE9WR6EHhq S13Iu55lNBiolmz1aB+O20LCrpHGWTefsirl3A/JVfIjZ1VsaQR6GgGnonB3fNBUuR 09a4uh+/Xa4qflhIocFS59lNlxOC6lHSMr65aKN7JTIHW/2VSb4BvnT/U46NQWe2Ms zyifoFDh/qM0QkYHk8ZNXShKzZheO+DQjlmWKyO8nmBXQJbGad+hGsCMBiRtJYpjmr b8PcXMVrejp5tuTmxfO+YYoevt449INrzXkCod118HUIr6e54SAv0Pnm4970VpJvXU 3evp3KAdpVYYg== Message-ID: <33ade507-a389-4ace-8635-a4cd63904a16@kernel.org> Date: Tue, 18 Aug 2026 09:41:40 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH net v2] dpll: fix NULL deref in dpll_device_ops() during teardown race Content-Language: fr To: Petr Oros , netdev@vger.kernel.org Cc: Vadim Fedorenko , Arkadiusz Kubalewski , Jiri Pirko , Michal Michalik , Milena Olech , linux-kernel@vger.kernel.org, ivecera@redhat.com References: <20260813140817.1051388-1-poros@redhat.com> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Petr, On 13/08/2026 16:08, Petr Oros wrote: > When the last owner of a dpll device unregisters while a foreign driver > still holds a pin on it via dpll_pin_on_pin_register(), the dpll object > stays alive with an empty registration list. A pin notification queued > before the unregister (e.g. ice reacting to zl3073x_i2c removal) then > walks pin->dpll_refs into dpll_device_ops(), which trips the WARN_ON and > dereferences the missing registration. dpll_lock cannot help because the > notification work was queued before the unregistering driver took the > lock. > > Treat the empty registration list as a legitimate transient state. Make > dpll_priv() and dpll_device_ops() return NULL in that case and make > every pin netlink path that resolves a device from a pin skip such > dplls. dpll_cmd_pin_get_one() picks a ref with a live registration and > returns -ENODEV when there is none, the pin dumpit skips such a pin > instead of aborting the dump, dpll_msg_add_pin_dplls() and the > frequency, esync, reference sync and phase adjust set paths skip dead > refs, and dpll_pin_parent_device_set() validates the parent with > dpll_device_get_by_id(). dpll_pin_register() is the last caller that > dereferenced the device ops without a check, so move its frequency > monitor validation under dpll_lock and tolerate a missing registration > there as well. > > The empty registration list is equivalent to a cleared DPLL_REGISTERED > mark, both transitions happen under dpll_lock in dpll_device_register() > and dpll_device_unregister(). A pin notification for a pin whose dplls > are all gone is now dropped with -ENODEV instead of crashing, all > callers in the core ignore that return value. Thank you for the patch. When merging net into net-next, it looks like it creates a lot of conflicts, mainly with commit 84e85c325e5e ("dpll: use pin owner's dpll ref for pin-level attribute setting"). Because the logic seems quite different now, do you mind providing instructions on how to resolve these conflicts, please? A 3-way patch and/or rerere artifacts could also help. Cheers, Matt -- Sponsored by the NGI0 Core fund.