From patchwork Mon Jul 12 06:08:16 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 473949 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, 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 EF0A3C07E9C for ; Mon, 12 Jul 2021 07:13:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DC61C61153 for ; Mon, 12 Jul 2021 07:13:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242897AbhGLHQd (ORCPT ); Mon, 12 Jul 2021 03:16:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:48836 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243482AbhGLHPr (ORCPT ); Mon, 12 Jul 2021 03:15:47 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9010B61409; Mon, 12 Jul 2021 07:12:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626073945; bh=2GSrmxk/D5DTqfdx5V5PejTHTpKTn6TNsAo3GA9JEds=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CsrHtYttJc4tPvYAT9Rsa4gxKDUSD+7LuSzZxqRT1+PXrCWdy1rJoqHWrBiOoAS00 d6dEUSrmDQ9zoh+UDOYB6JGz9xiK9bTXph0yd16vRWtwvi8x5MvnZkBalTEQgF0E8y JLPQCNGFi25DbHPI+15LW+wTfnqQylker9bML+/w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hang Zhang , Jia-Ju Bai , Kalle Valo , Sasha Levin Subject: [PATCH 5.12 413/700] cw1200: Revert unnecessary patches that fix unreal use-after-free bugs Date: Mon, 12 Jul 2021 08:08:16 +0200 Message-Id: <20210712061020.324296012@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060924.797321836@linuxfoundation.org> References: <20210712060924.797321836@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Hang Zhang [ Upstream commit 3f60f4685699aa6006e58e424637e8e413e0a94d ] A previous commit 4f68ef64cd7f ("cw1200: Fix concurrency use-after-free bugs in cw1200_hw_scan()") tried to fix a seemingly use-after-free bug between cw1200_bss_info_changed() and cw1200_hw_scan(), where the former frees a sk_buff pointed to by frame.skb, and the latter accesses the sk_buff pointed to by frame.skb. However, this issue should be a false alarm because: (1) "frame.skb" is not a shared variable between the above two functions, because "frame" is a local function variable, each of the two functions has its own local "frame" - they just happen to have the same variable name. (2) the sk_buff(s) pointed to by these two "frame.skb" are also two different object instances, they are individually allocated by different dev_alloc_skb() within the two above functions. To free one object instance will not invalidate the access of another different one. Based on these facts, the previous commit should be unnecessary. Moreover, it also introduced a missing unlock which was addressed in a subsequent commit 51c8d24101c7 ("cw1200: fix missing unlock on error in cw1200_hw_scan()"). Now that the original use-after-free is unreal, these two commits should be reverted. This patch performs the reversion. Fixes: 4f68ef64cd7f ("cw1200: Fix concurrency use-after-free bugs in cw1200_hw_scan()") Fixes: 51c8d24101c7 ("cw1200: fix missing unlock on error in cw1200_hw_scan()") Signed-off-by: Hang Zhang Acked-by: Jia-Ju Bai Signed-off-by: Kalle Valo Link: https://lore.kernel.org/r/20210521223238.25020-1-zh.nvgt@gmail.com Signed-off-by: Sasha Levin --- drivers/net/wireless/st/cw1200/scan.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/drivers/net/wireless/st/cw1200/scan.c b/drivers/net/wireless/st/cw1200/scan.c index 988581cc134b..1f856fbbc0ea 100644 --- a/drivers/net/wireless/st/cw1200/scan.c +++ b/drivers/net/wireless/st/cw1200/scan.c @@ -75,30 +75,27 @@ int cw1200_hw_scan(struct ieee80211_hw *hw, if (req->n_ssids > WSM_SCAN_MAX_NUM_OF_SSIDS) return -EINVAL; - /* will be unlocked in cw1200_scan_work() */ - down(&priv->scan.lock); - mutex_lock(&priv->conf_mutex); - frame.skb = ieee80211_probereq_get(hw, priv->vif->addr, NULL, 0, req->ie_len); - if (!frame.skb) { - mutex_unlock(&priv->conf_mutex); - up(&priv->scan.lock); + if (!frame.skb) return -ENOMEM; - } if (req->ie_len) skb_put_data(frame.skb, req->ie, req->ie_len); + /* will be unlocked in cw1200_scan_work() */ + down(&priv->scan.lock); + mutex_lock(&priv->conf_mutex); + ret = wsm_set_template_frame(priv, &frame); if (!ret) { /* Host want to be the probe responder. */ ret = wsm_set_probe_responder(priv, true); } if (ret) { - dev_kfree_skb(frame.skb); mutex_unlock(&priv->conf_mutex); up(&priv->scan.lock); + dev_kfree_skb(frame.skb); return ret; } @@ -120,8 +117,8 @@ int cw1200_hw_scan(struct ieee80211_hw *hw, ++priv->scan.n_ssids; } - dev_kfree_skb(frame.skb); mutex_unlock(&priv->conf_mutex); + dev_kfree_skb(frame.skb); queue_work(priv->workqueue, &priv->scan.work); return 0; }