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 2900C1E522; Thu, 30 Jan 2025 14:26:32 +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=1738247192; cv=none; b=iED/d6iET4j64wkPslvzqatUW9x5GZaSfZs4MGseqWn1wfYkUwhHCvGlc1qIfbXFwPrCntI/kDZhedci6XEGpdE3kMvY79f5o2MYlPhB/UaGdtOgP2a52oqpjs80USaBYe1zXYYjxssmaH2tUwP+kcHqnq4HM73GfmuepMAqKb8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738247192; c=relaxed/simple; bh=P9JOufGnYVwfwba3QyNh765ejfMewHcW2532r1eYiBU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eogrC7VEJivyIKTrAMLKV4EAw8bufC0tJ4zuIe7JdtmQj0nDl0vl35Y8AD1edcuK0wv6hxQFkBOsYX3P1IN1zazfWcme4r49iURHWllwZgtJJ/wt7MyDgh15FIguI8gBeQGoj11tGsemtAnS3eGf+fMp29k8Ifc2deFoixU2Ax4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=nf2OoBVl; 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="nf2OoBVl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D1CCC4CED2; Thu, 30 Jan 2025 14:26:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1738247192; bh=P9JOufGnYVwfwba3QyNh765ejfMewHcW2532r1eYiBU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nf2OoBVlu6t5qKqOclsl4TgRXca18lzNNn8hRVYM2qZ0FNzU6PXffbJbLThX84goV plsBVA/L0n5FcJi2g5nkKLq9F6IHsbtJIsdrm6ckAcCUbTxqlK/6dfkb2LR3cNrKj2 Vu2PZOLtUWscgKjpqoIOKhB3rqaMctXzCStJh3Cc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zhongqiu Han , Bartosz Golaszewski , Bruno VERNAY , Hugo SIMELIERE Subject: [PATCH 5.10 096/133] gpiolib: cdev: Fix use after free in lineinfo_changed_notify Date: Thu, 30 Jan 2025 15:01:25 +0100 Message-ID: <20250130140146.394623527@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250130140142.491490528@linuxfoundation.org> References: <20250130140142.491490528@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zhongqiu Han commit 02f6b0e1ec7e0e7d059dddc893645816552039da upstream. The use-after-free issue occurs as follows: when the GPIO chip device file is being closed by invoking gpio_chrdev_release(), watched_lines is freed by bitmap_free(), but the unregistration of lineinfo_changed_nb notifier chain failed due to waiting write rwsem. Additionally, one of the GPIO chip's lines is also in the release process and holds the notifier chain's read rwsem. Consequently, a race condition leads to the use-after-free of watched_lines. Here is the typical stack when issue happened: [free] gpio_chrdev_release() --> bitmap_free(cdev->watched_lines) <-- freed --> blocking_notifier_chain_unregister() --> down_write(&nh->rwsem) <-- waiting rwsem --> __down_write_common() --> rwsem_down_write_slowpath() --> schedule_preempt_disabled() --> schedule() [use] st54spi_gpio_dev_release() --> gpio_free() --> gpiod_free() --> gpiod_free_commit() --> gpiod_line_state_notify() --> blocking_notifier_call_chain() --> down_read(&nh->rwsem); <-- held rwsem --> notifier_call_chain() --> lineinfo_changed_notify() --> test_bit(xxxx, cdev->watched_lines) <-- use after free The side effect of the use-after-free issue is that a GPIO line event is being generated for userspace where it shouldn't. However, since the chrdev is being closed, userspace won't have the chance to read that event anyway. To fix the issue, call the bitmap_free() function after the unregistration of lineinfo_changed_nb notifier chain. Fixes: 51c1064e82e7 ("gpiolib: add new ioctl() for monitoring changes in line info") Signed-off-by: Zhongqiu Han Link: https://lore.kernel.org/r/20240505141156.2944912-1-quic_zhonhan@quicinc.com Signed-off-by: Bartosz Golaszewski Signed-off-by: Bruno VERNAY Signed-off-by: Hugo SIMELIERE Signed-off-by: Greg Kroah-Hartman --- drivers/gpio/gpiolib-cdev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -2352,9 +2352,9 @@ static int gpio_chrdev_release(struct in struct gpio_chardev_data *cdev = file->private_data; struct gpio_device *gdev = cdev->gdev; - bitmap_free(cdev->watched_lines); blocking_notifier_chain_unregister(&gdev->notifier, &cdev->lineinfo_changed_nb); + bitmap_free(cdev->watched_lines); put_device(&gdev->dev); kfree(cdev);