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 AF1352DB78B; Sat, 18 Apr 2026 16:22:29 +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=1776529349; cv=none; b=DrO7EZkuaohyMo7w9FnurZGVn4ZDSaLSW1x0y1gg3vHMWiqjiz3WyJUrJ5VH3kXAgP3Sma8ZLGIw8+UtNx1rtUwDgKWN23DsOpxLAnHJH+y7Jchxbf7naYSZdRolTIMCymXS0iQl4sSYFmFc+jdxgbNbIp5m97KWr7tDGavt4TQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776529349; c=relaxed/simple; bh=PswHVbHtH9imVCnuyWxVZ9hWTCCTHUzCVk1/nGwP2PE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=H453LmXp6S5CxPGMcy4CYuacCrmzK6U0hLTcQZtvxFWf83xBuXss4NaO8ViiNPdHnZZLWbiK6G5ox7wDZ6ycHLTgwfchPkXgIdq5vKW6e7uD0jBP4XaGgZQjWvSnPZkCReFrtMI0nhyvy+vwPzToO6VF08Yqofc5xMk9JpOW6n4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ja7utCVG; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Ja7utCVG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C049AC19424; Sat, 18 Apr 2026 16:22:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776529349; bh=PswHVbHtH9imVCnuyWxVZ9hWTCCTHUzCVk1/nGwP2PE=; h=From:To:Cc:Subject:Date:From; b=Ja7utCVGzOqrrirFqmtbR+rRtB8vYEZ9+HAPa7W3QZoMxvBJk/1rvhUnISt9jY4B2 qzt6xdvwTSAXn+RrhB4aPC4h2+ws9AH+d3kMe1nlSyV0P9vhvLLiyLGJmKH7Y1JDUX StaUq3E48zJZyAJPRM5zEPjdwp/t+tkFyPtEpH2NxiKEEYLKYVpnQQaVTTqw3r91CP +MGkw3dVg4Fkx/58gQo02IvWyy3OxCBiP5EsKoJ/JHvMKSLNDWPNhzcmyRlT41IhAd 8IWsZP8fF8lkUNc+oogbVRcxH/lik8JwGtDmESQWcVQevyj48XQApzlF2dm1n5NZ0W xptcElkyXRexA== From: Danilo Krummrich To: gregkh@linuxfoundation.org, rafael@kernel.org, saravanak@kernel.org, ulf.hansson@linaro.org Cc: driver-core@lists.linux.dev, linux-kernel@vger.kernel.org, Danilo Krummrich Subject: [PATCH] driver core: use READ_ONCE() for dev->driver in dev_has_sync_state() Date: Sat, 18 Apr 2026 18:22:18 +0200 Message-ID: <20260418162221.1121873-1-dakr@kernel.org> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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