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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 C99CEC43603 for ; Mon, 16 Dec 2019 17:57:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A21B321582 for ; Mon, 16 Dec 2019 17:57:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576519070; bh=M1JzpKtZpN9DJmcRO5JXbqZWhucdZ+QA9NRbNBHcyQM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=YUpTSvHjOQRwiM7AO+05rvAVNLwiFN0ocvrOJfdzAxAcIVrsKf62BMk2ZkjOueALD U8WUL3aUfJRIkqq3/z7fs2qIq0LIsYDAN2cTPuajTrNk9ncH7CSKt4UM0ChHcpicwT VZs1+xxBjWB+IYHuRS4Wo9VMo90bLPrkDsZkifEQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727872AbfLPR5t (ORCPT ); Mon, 16 Dec 2019 12:57:49 -0500 Received: from mail.kernel.org ([198.145.29.99]:56900 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728282AbfLPR5r (ORCPT ); Mon, 16 Dec 2019 12:57:47 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BC0352166E; Mon, 16 Dec 2019 17:57:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576519066; bh=M1JzpKtZpN9DJmcRO5JXbqZWhucdZ+QA9NRbNBHcyQM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sidro71qzSCuhQtIADqmlB8/RuKgDP3F3/b1EcrEvoS1KP/3tpMCIRUGbBc7U2Cqj CgsmfEp09ffp3/tH589P+5CUouopUnOoTrnToWNktWx50LQN1mSeyDyrBWvGsc8IHC Zk6DwdKBAy5v0La9bVkgct3lB+tq596cghaDQSrY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pete Zaitcev , syzbot+56f9673bb4cdcbeb0e92@syzkaller.appspotmail.com, Alan Stern Subject: [PATCH 4.14 180/267] usb: mon: Fix a deadlock in usbmon between mmap and read Date: Mon, 16 Dec 2019 18:48:26 +0100 Message-Id: <20191216174912.361705501@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20191216174848.701533383@linuxfoundation.org> References: <20191216174848.701533383@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pete Zaitcev commit 19e6317d24c25ee737c65d1ffb7483bdda4bb54a upstream. The problem arises because our read() function grabs a lock of the circular buffer, finds something of interest, then invokes copy_to_user() straight from the buffer, which in turn takes mm->mmap_sem. In the same time, the callback mon_bin_vma_fault() is invoked under mm->mmap_sem. It attempts to take the fetch lock and deadlocks. This patch does away with protecting of our page list with any semaphores, and instead relies on the kernel not close the device while mmap is active in a process. In addition, we prohibit re-sizing of a buffer while mmap is active. This way, when (now unlocked) fault is processed, it works with the page that is intended to be mapped-in, and not some other random page. Note that this may have an ABI impact, but hopefully no legitimate program is this wrong. Signed-off-by: Pete Zaitcev Reported-by: syzbot+56f9673bb4cdcbeb0e92@syzkaller.appspotmail.com Reviewed-by: Alan Stern Fixes: 46eb14a6e158 ("USB: fix usbmon BUG trigger") Cc: Link: https://lore.kernel.org/r/20191204203941.3503452b@suzdal.zaitcev.lan Signed-off-by: Greg Kroah-Hartman --- drivers/usb/mon/mon_bin.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-) --- a/drivers/usb/mon/mon_bin.c +++ b/drivers/usb/mon/mon_bin.c @@ -1038,12 +1038,18 @@ static long mon_bin_ioctl(struct file *f mutex_lock(&rp->fetch_lock); spin_lock_irqsave(&rp->b_lock, flags); - mon_free_buff(rp->b_vec, rp->b_size/CHUNK_SIZE); - kfree(rp->b_vec); - rp->b_vec = vec; - rp->b_size = size; - rp->b_read = rp->b_in = rp->b_out = rp->b_cnt = 0; - rp->cnt_lost = 0; + if (rp->mmap_active) { + mon_free_buff(vec, size/CHUNK_SIZE); + kfree(vec); + ret = -EBUSY; + } else { + mon_free_buff(rp->b_vec, rp->b_size/CHUNK_SIZE); + kfree(rp->b_vec); + rp->b_vec = vec; + rp->b_size = size; + rp->b_read = rp->b_in = rp->b_out = rp->b_cnt = 0; + rp->cnt_lost = 0; + } spin_unlock_irqrestore(&rp->b_lock, flags); mutex_unlock(&rp->fetch_lock); } @@ -1215,13 +1221,21 @@ mon_bin_poll(struct file *file, struct p static void mon_bin_vma_open(struct vm_area_struct *vma) { struct mon_reader_bin *rp = vma->vm_private_data; + unsigned long flags; + + spin_lock_irqsave(&rp->b_lock, flags); rp->mmap_active++; + spin_unlock_irqrestore(&rp->b_lock, flags); } static void mon_bin_vma_close(struct vm_area_struct *vma) { + unsigned long flags; + struct mon_reader_bin *rp = vma->vm_private_data; + spin_lock_irqsave(&rp->b_lock, flags); rp->mmap_active--; + spin_unlock_irqrestore(&rp->b_lock, flags); } /* @@ -1233,16 +1247,12 @@ static int mon_bin_vma_fault(struct vm_f unsigned long offset, chunk_idx; struct page *pageptr; - mutex_lock(&rp->fetch_lock); offset = vmf->pgoff << PAGE_SHIFT; - if (offset >= rp->b_size) { - mutex_unlock(&rp->fetch_lock); + if (offset >= rp->b_size) return VM_FAULT_SIGBUS; - } chunk_idx = offset / CHUNK_SIZE; pageptr = rp->b_vec[chunk_idx].pg; get_page(pageptr); - mutex_unlock(&rp->fetch_lock); vmf->page = pageptr; return 0; }