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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,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 0790DC4338F for ; Fri, 6 Aug 2021 12:15:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E1AB26113C for ; Fri, 6 Aug 2021 12:15:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343651AbhHFMPn (ORCPT ); Fri, 6 Aug 2021 08:15:43 -0400 Received: from out30-45.freemail.mail.aliyun.com ([115.124.30.45]:59656 "EHLO out30-45.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343589AbhHFMPl (ORCPT ); Fri, 6 Aug 2021 08:15:41 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R351e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04400;MF=xianting.tian@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0Ui8W5Kx_1628252123; Received: from localhost(mailfrom:xianting.tian@linux.alibaba.com fp:SMTPD_---0Ui8W5Kx_1628252123) by smtp.aliyun-inc.com(127.0.0.1); Fri, 06 Aug 2021 20:15:24 +0800 From: Xianting Tian To: jassisinghbrar@gmail.com Cc: linux-kernel@vger.kernel.org, guoren@kernel.org, Xianting Tian Subject: [PATCH] mailbox: fix a UAF bug in msg_submit() Date: Fri, 6 Aug 2021 20:15:21 +0800 Message-Id: <20210806121521.124365-1-xianting.tian@linux.alibaba.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We met a UAF issue during our mailbox testing. In synchronous mailbox, we use mbox_send_message() to send a message and wait for completion. mbox_send_message() calls msg_submit() to send the message for the first time, if timeout, it will send the message in tx_tick() for the second time. We assume message sending failed for both two times, then the message will be still in the internal buffer of a chan(chan->msg_data[idx]). It will be send again in the same way when mbox_send_message() is called next time. But, at this time this message (chan->msg_data[idx]) may be a UAF pointer, as the message is passed to mailbox core by user. User may free it after last calling of mbox_send_message() returned or not. Who knows!!! In this patch, if the first time sending timeout, we pass timeout info(-ETIME) to msg_submit() when do the second time sending by tx_tick(). If it still send failed (chan->mbox->ops->send_data() returned non-zero value) in the second time, we will give up this message(chan->msg_count--) sending. It doesn't matter, user can chose to send it again. Actually, the issue I described above doesn't exist if 'chan->mbox->ops->send_data()' always return 0. Because if it always returns 0, we will always do 'chan->msg_count—' regardless of message sending success or failure. We have such mailbox driver, for example, hi6220_mbox_send_data() always return 0. But we still have mailbox drivers, which don't always return 0, for example, flexrm_send_data() of drivers/mailbox/bcm-flexrm-mailbox.c. Signed-off-by: Xianting Tian --- drivers/mailbox/mailbox.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c index 3e7d4b20a..3e010aafa 100644 --- a/drivers/mailbox/mailbox.c +++ b/drivers/mailbox/mailbox.c @@ -50,7 +50,7 @@ static int add_to_rbuf(struct mbox_chan *chan, void *mssg) return idx; } -static void msg_submit(struct mbox_chan *chan) +static void msg_submit(struct mbox_chan *chan, int last_submit) { unsigned count, idx; unsigned long flags; @@ -75,7 +75,7 @@ static void msg_submit(struct mbox_chan *chan) chan->cl->tx_prepare(chan->cl, data); /* Try to submit a message to the MBOX controller */ err = chan->mbox->ops->send_data(chan, data); - if (!err) { + if (!err || last_submit == -ETIME) { chan->active_req = data; chan->msg_count--; } @@ -101,7 +101,7 @@ static void tx_tick(struct mbox_chan *chan, int r) spin_unlock_irqrestore(&chan->lock, flags); /* Submit next message */ - msg_submit(chan); + msg_submit(chan, r); if (!mssg) return; @@ -260,7 +260,7 @@ int mbox_send_message(struct mbox_chan *chan, void *mssg) return t; } - msg_submit(chan); + msg_submit(chan, 0); if (chan->cl->tx_block) { unsigned long wait; -- 2.17.1