From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45997) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eykJp-0006Xy-Md for qemu-devel@nongnu.org; Wed, 21 Mar 2018 16:26:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eykJo-00012p-N8 for qemu-devel@nongnu.org; Wed, 21 Mar 2018 16:26:45 -0400 References: <20180321200114.10981-1-jsnow@redhat.com> From: Eric Blake Message-ID: Date: Wed, 21 Mar 2018 15:26:29 -0500 MIME-Version: 1.0 In-Reply-To: <20180321200114.10981-1-jsnow@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH for-2.12 v5] file-posix: specify expected filetypes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: John Snow , qemu-block@nongnu.org Cc: kwolf@redhat.com, qemu-devel@nongnu.org, Max Reitz On 03/21/2018 03:01 PM, John Snow wrote: > Adjust each caller of raw_open_common to specify if they are expecting > host and character devices or not. Tighten expectations of file types upon > open in the common code and refuse types that are not expected. > > This has two effects: > > (1) Character and block devices are now considered deprecated for the > 'file' driver, which expects only S_IFREG, and Which may have interesting effects on v2v's attempt to use qemu-img on /dev/null as a quick feature probe of qemu-img... https://lists.gnu.org/archive/html/qemu-devel/2018-03/msg05753.html but we may want to special-case that one in a separate patch. > (2) no file-posix driver (file, host_cdrom, or host_device) can open > directories now. > > I don't think there's a legitimate reason to open directories as if > they were files. This prevents QEMU from opening and attempting to probe > a directory inode, which can break in exciting ways. One of those ways > is lseek on ext4/xfs, which will return 0x7fffffffffffffff as the file > size instead of EISDIR. This can coax QEMU into responding with a > confusing "file too big" instead of "Hey, that's not a file". > > See: https://bugs.launchpad.net/qemu/+bug/1739304/ > Signed-off-by: John Snow > --- > > v5: rebase for 2.12.0-rc0 Still makes sense as a 2.12 bugfix. Reviewed-by: Eric Blake -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org