From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9342D272E56; Sun, 19 Apr 2026 14:40:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776609639; cv=none; b=BsT/bBecoI7g6F2bjMzuYO/bg7KNrA3pkIZnHxl90Fa3oMU+F882Zx5za0AZ5GFGvt+JA6CeAk9864dWJuxbx24VgNPGIJ3B+WvOgC/1/8AwSmHAWG4ifK+18nzL4h69N9sytk0cWTNUPG6wxx/9BPYXc0zH8dmdvrybvMIvQ2E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776609639; c=relaxed/simple; bh=WEpLdFHZM1W42OrHbEBmve2xno7jxX9Bw++wSJcO1YA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=NtvofEzZcZ2b8WslaLmQn/oN04Dq4RHF7cKHQ9mccPVoKEJdlx9dQoN/bEheSrP7STPauJ8kllgRmwVDxpW0HmpMwVEqheYSgO3yThhC+LvwIqYH8gvdkg+aLCwGd875wuYk5tGSlGYgUuvhfCUUkM5RXgWhU9lpL3x6++bg6gw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=DyHjLIWX; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="DyHjLIWX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 18F14C2BCAF; Sun, 19 Apr 2026 14:40:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776609639; bh=WEpLdFHZM1W42OrHbEBmve2xno7jxX9Bw++wSJcO1YA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=DyHjLIWXIlGh5aZI0v1PeGayWW6ezw63n68pXJMjhZ6Q1rx9nfyjErLT9QWqPR5Wu WO+wO07eOiYIsY/i62ICgZ3vrH+aDTmENcmRXiCSt7jWsrE+c5vn5l8UkNCZci3kuM C53CqoRlHlGuPCknRISKZwidPJkRVjPWSAjTIFbw= Date: Sun, 19 Apr 2026 16:40:36 +0200 From: Greg KH To: Danilo Krummrich Cc: rafael@kernel.org, saravanak@kernel.org, ulf.hansson@linaro.org, driver-core@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH] driver core: use READ_ONCE() for dev->driver in dev_has_sync_state() Message-ID: <2026041930-evade-mockup-b243@gregkh> References: <20260418162221.1121873-1-dakr@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260418162221.1121873-1-dakr@kernel.org> On Sat, Apr 18, 2026 at 06:22:18PM +0200, Danilo Krummrich wrote: > dev_has_sync_state() reads dev->driver twice without holding > device_lock() -- once for the NULL check and once to dereference > ->sync_state. Some callers only hold device_links_write_lock, which > doesn't prevent a concurrent unbind from clearing dev->driver via > device_unbind_cleanup(). > > Fix it by reading dev->driver exactly once with READ_ONCE(), pairing > with the WRITE_ONCE() in device_set_driver(). > > Link: https://lore.kernel.org/driver-core/DHW8QPU1VU1F.3P6PH69HLFBYC@kernel.org/ > Fixes: ac338acf514e ("driver core: Add dev_has_sync_state()") > Signed-off-by: Danilo Krummrich > --- > include/linux/device.h | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/include/linux/device.h b/include/linux/device.h > index ac972e7bead4..4c1c9cb8570a 100644 > --- a/include/linux/device.h > +++ b/include/linux/device.h > @@ -1018,9 +1018,12 @@ static inline void device_lock_assert(struct device *dev) > > static inline bool dev_has_sync_state(struct device *dev) > { > + struct device_driver *drv; > + > if (!dev) > return false; > - if (dev->driver && dev->driver->sync_state) > + drv = READ_ONCE(dev->driver); > + if (drv && drv->sync_state) > return true; > if (dev->bus && dev->bus->sync_state) > return true; > > base-commit: 5b484311507b5d403c1f7a45f6aa3778549e268b > -- > 2.53.0 > > Acked-by: Greg Kroah-Hartman