From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B778C4338F for ; Wed, 28 Jul 2021 08:51:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0777960FF3 for ; Wed, 28 Jul 2021 08:51:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235376AbhG1Ivx (ORCPT ); Wed, 28 Jul 2021 04:51:53 -0400 Received: from sender4-of-o53.zoho.com ([136.143.188.53]:21306 "EHLO sender4-of-o53.zoho.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234311AbhG1Ivw (ORCPT ); Wed, 28 Jul 2021 04:51:52 -0400 ARC-Seal: i=1; a=rsa-sha256; t=1627462306; cv=none; d=zohomail.com; s=zohoarc; b=QHAUmBTfA2qpH3gQA8A60HpDn5fvmwj6aHPyuJVTO0pOz3sdm/QK7+SImkvqGTW59TKlhhuvEtiyRJFRdBaxcIwKZNx68JVlWiD4tS7AOv3ml+zKTb2khSo8AjlV1+4u1chC/UCp6uk3eVqTm+8K1Ss9xhh4anj7zYFKr/4b2ww= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1627462306; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:To; bh=gsjED1qUWFvsvQhs+gLZzWpKQkBhUHE6F1fvCf133bw=; b=f3ANO5CXgtvEStNmIZs/aJH+LQhOdNM42UUTIaupkTD0rAuXixq8idAdbYsO7dxLOLH4LGwp7qiA11ZbfatpbM6DM9n5oXZttsn9340UEvVRL1SxQWygzPaL0KhgM9uYSiTpMTBHC+VquB36rY9SLZ97+GvrWK+YfZUBXP3rwZY= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=anirudhrb.com; spf=pass smtp.mailfrom=mail@anirudhrb.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1627462306; s=zoho; d=anirudhrb.com; i=mail@anirudhrb.com; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=gsjED1qUWFvsvQhs+gLZzWpKQkBhUHE6F1fvCf133bw=; b=Xht6UV/iDUMmjCJasQRobar4Ug7ZZPYDSaEDjCsiRuTuX+840YB5LRv5kg5slsia Jnlg+2qwlEezTcDOr4kX/dIAdEVAfq2iBgUkvFRTOLKWZJBj9VEUgsQ+8duFCYZuXdq 8LfCbN7sRPY2dT/l9S1tyN9zauFLckUgREOLlPSE= Received: from localhost.localdomain (49.207.59.170 [49.207.59.170]) by mx.zohomail.com with SMTPS id 1627462303398561.6572059199414; Wed, 28 Jul 2021 01:51:43 -0700 (PDT) From: Anirudh Rayabharam To: mcgrof@kernel.org, gregkh@linuxfoundation.org, rafael@kernel.org, skhan@linuxfoundation.org Cc: Anirudh Rayabharam , linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, syzbot+de271708674e2093097b@syzkaller.appspotmail.com Subject: [PATCH v8 2/2] firmware_loader: fix use-after-free in firmware_fallback_sysfs Date: Wed, 28 Jul 2021 14:21:07 +0530 Message-Id: <20210728085107.4141-3-mail@anirudhrb.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210728085107.4141-1-mail@anirudhrb.com> References: <20210728085107.4141-1-mail@anirudhrb.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-ZohoMailClient: External Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This use-after-free happens when a fw_priv object has been freed but hasn't been removed from the pending list (pending_fw_head). The next time fw_load_sysfs_fallback tries to insert into the list, it ends up accessing the pending_list member of the previously freed fw_priv. The root cause here is that all code paths that abort the fw load don't delete it from the pending list. For example: _request_firmware() -> fw_abort_batch_reqs() -> fw_state_aborted() To fix this, delete the fw_priv from the list in __fw_set_state() if the new state is DONE or ABORTED. This way, all aborts will remove the fw_priv from the list. Accordingly, remove calls to list_del_init that were being made before calling fw_state_(aborted|done). Also, in fw_load_sysfs_fallback, don't add the fw_priv to the pending list if it is already aborted. Instead, just jump out and return early. Fixes: bcfbd3523f3c ("firmware: fix a double abort case with fw_load_sysfs_fallback") Reported-by: syzbot+de271708674e2093097b@syzkaller.appspotmail.com Tested-by: syzbot+de271708674e2093097b@syzkaller.appspotmail.com Acked-by: Luis Chamberlain Signed-off-by: Anirudh Rayabharam --- drivers/base/firmware_loader/fallback.c | 12 ++++++++---- drivers/base/firmware_loader/firmware.h | 10 +++++++++- drivers/base/firmware_loader/main.c | 2 ++ 3 files changed, 19 insertions(+), 5 deletions(-) diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c index 1a48be0a030e..d7d63c1aa993 100644 --- a/drivers/base/firmware_loader/fallback.c +++ b/drivers/base/firmware_loader/fallback.c @@ -89,12 +89,11 @@ static void __fw_load_abort(struct fw_priv *fw_priv) { /* * There is a small window in which user can write to 'loading' - * between loading done and disappearance of 'loading' + * between loading done/aborted and disappearance of 'loading' */ - if (fw_sysfs_done(fw_priv)) + if (fw_state_is_aborted(fw_priv) || fw_sysfs_done(fw_priv)) return; - list_del_init(&fw_priv->pending_list); fw_state_aborted(fw_priv); } @@ -280,7 +279,6 @@ static ssize_t firmware_loading_store(struct device *dev, * Same logic as fw_load_abort, only the DONE bit * is ignored and we set ABORT only on failure. */ - list_del_init(&fw_priv->pending_list); if (rc) { fw_state_aborted(fw_priv); written = rc; @@ -513,6 +511,11 @@ static int fw_load_sysfs_fallback(struct fw_sysfs *fw_sysfs, long timeout) } mutex_lock(&fw_lock); + if (fw_state_is_aborted(fw_priv)) { + mutex_unlock(&fw_lock); + retval = -EINTR; + goto out; + } list_add(&fw_priv->pending_list, &pending_fw_head); mutex_unlock(&fw_lock); @@ -538,6 +541,7 @@ static int fw_load_sysfs_fallback(struct fw_sysfs *fw_sysfs, long timeout) } else if (fw_priv->is_paged_buf && !fw_priv->data) retval = -ENOMEM; +out: device_del(f_dev); err_put_dev: put_device(f_dev); diff --git a/drivers/base/firmware_loader/firmware.h b/drivers/base/firmware_loader/firmware.h index 63bd29fdcb9c..a3014e9e2c85 100644 --- a/drivers/base/firmware_loader/firmware.h +++ b/drivers/base/firmware_loader/firmware.h @@ -117,8 +117,16 @@ static inline void __fw_state_set(struct fw_priv *fw_priv, WRITE_ONCE(fw_st->status, status); - if (status == FW_STATUS_DONE || status == FW_STATUS_ABORTED) + if (status == FW_STATUS_DONE || status == FW_STATUS_ABORTED) { +#ifdef CONFIG_FW_LOADER_USER_HELPER + /* + * Doing this here ensures that the fw_priv is deleted from + * the pending list in all abort/done paths. + */ + list_del_init(&fw_priv->pending_list); +#endif complete_all(&fw_st->completion); + } } static inline void fw_state_aborted(struct fw_priv *fw_priv) diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c index 4fdb8219cd08..68c549d71230 100644 --- a/drivers/base/firmware_loader/main.c +++ b/drivers/base/firmware_loader/main.c @@ -783,8 +783,10 @@ static void fw_abort_batch_reqs(struct firmware *fw) return; fw_priv = fw->priv; + mutex_lock(&fw_lock); if (!fw_state_is_aborted(fw_priv)) fw_state_aborted(fw_priv); + mutex_unlock(&fw_lock); } /* called from request_firmware() and request_firmware_work_func() */ -- 2.26.2