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=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 92189C433E0 for ; Wed, 17 Feb 2021 15:32:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 50D6A64DA1 for ; Wed, 17 Feb 2021 15:32:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233744AbhBQPcn (ORCPT ); Wed, 17 Feb 2021 10:32:43 -0500 Received: from mail.kernel.org ([198.145.29.99]:50334 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233617AbhBQP0f (ORCPT ); Wed, 17 Feb 2021 10:26:35 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8425D64E2F; Wed, 17 Feb 2021 15:15:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1613574942; bh=lUUgSVw9D08H8NDbvmHh26K4kGOfdxzcmJG/Pnu8YKE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=b/JgNwWCzLwj1i23ERdJVTBxyfis/Ov1h9bMmhmZjxabjDMginjnI7BkiGPhrWGre EKZVt097yJI9nUvmyd9MIK3ycqZA2TqMEBjf5S/AuTWMSQrjXXETpHPxukgBC/0Yjj BeVmcr0oaxwHa4xh0vSx6dMaIHT4+N3v7NaEznKQ= Date: Wed, 17 Feb 2021 16:15:39 +0100 From: Greg KH To: Sabyrzhan Tasbolatov Cc: jirislaby@kernel.org, linux-kernel@vger.kernel.org, syzbot+3d2c27c2b7dc2a94814d@syzkaller.appspotmail.com Subject: Re: [PATCH] tty: fix when iov_iter_count() returns 0 in tty_write() Message-ID: References: <20210217144347.2962551-1-snovitoll@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 17, 2021 at 04:13:58PM +0100, Greg KH wrote: > On Wed, Feb 17, 2021 at 08:43:47PM +0600, Sabyrzhan Tasbolatov wrote: > > syzbot found WARNING in iov_iter_revert[1] when iov_iter_count() returns 0, > > therefore INT_MAX is passed to iov_iter_revert() causing > MAX_RW_COUNT > > warning. > > > > static inline ssize_t do_tty_write() > > { > > .. > > size_t count = iov_iter_count(from); > > .. > > size_t size = count; > > if (ret != size) > > iov_iter_revert(from, size-ret); > > > > [1] WARNING: lib/iov_iter.c:1090 > > Call Trace: > > do_tty_write drivers/tty/tty_io.c:967 [inline] > > file_tty_write.constprop.0+0x55f/0x8f0 drivers/tty/tty_io.c:1048 > > call_write_iter include/linux/fs.h:1901 [inline] > > new_sync_write+0x426/0x650 fs/read_write.c:518 > > vfs_write+0x791/0xa30 fs/read_write.c:605 > > ksys_write+0x12d/0x250 fs/read_write.c:658 > > > > Fixes: 494e63ee9c("tty: implement write_iter") > > Nit, you need a ' ' before your '(' character here, otherwise the > linux-next scripts will complain. Also, you got the git commit id wrong, so this needs to be fixed up anyway. You are pointing to a merge point, I doubt that's what you want to point to here, right? thanks, greg k-h