Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755348AbaAFRth (ORCPT ); Mon, 6 Jan 2014 12:49:37 -0500 Received: from mail-ea0-f181.google.com ([209.85.215.181]:54108 "EHLO mail-ea0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755196AbaAFRtf (ORCPT ); Mon, 6 Jan 2014 12:49:35 -0500 Date: Mon, 6 Jan 2014 18:50:20 +0100 From: Miklos Szeredi To: "Darrick J. Wong" Cc: Alexander Viro , linux-fsdevel , fuse-devel@lists.sourceforge.net, linux-kernel , Richard Hansen Subject: Re: [fuse-devel] [PATCH v2] fuse: Fix IOC_[GS]ET{FLAGS, VERSION} argument size brokenness. Message-ID: <20140106175020.GG16230@tucsk.piliscsaba.szeredi.hu> References: <20131219232739.GA10192@birch.djwong.org> <20131220233534.GC10192@birch.djwong.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131220233534.GC10192@birch.djwong.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 20, 2013 at 03:35:34PM -0800, Darrick J. Wong wrote: > The IOC_[GS]ETFLAGS and IOC_[GS]ETVERSION ioctls, despite being > defined to take a "long" parameter, actually take "int" parameters. > FUSE unfortunately assumed that the ioctl definitions never lie, and FUSE doesn't really assume anything. It just says, that ioctl's that *properly* use the _IO* macros will work. Everything else will not. It's unfortunate that IOC_SET/GETFLAGS is something that may actually make sense on a fuse filesystem... Two ways out of this: A) Add quirks to fuse B) Add new, fixed ioctls and use those from chattr if available I'd very much prefer B. Thanks, Miklos > transfers a long's worth of data in and out of userspace, which causes > stack smashing in chattr, and other bugs elsewhere. > > So, special-case this in FUSE so that we don't crash userland. > > v2: Do the same for the IOC_[GS]ETVERSION ioctls, as Richard Hansen > points out. > > Signed-off-by: Darrick J. Wong > --- > fs/fuse/file.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/fs/fuse/file.c b/fs/fuse/file.c > index 7e70506..f8766ab 100644 > --- a/fs/fuse/file.c > +++ b/fs/fuse/file.c > @@ -2385,6 +2385,22 @@ long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg, > iov->iov_base = (void __user *)arg; > iov->iov_len = _IOC_SIZE(cmd); > > + /* > + * The IOC_[GS]ETFLAGS and IOC_[GS]ETVERSION ioctls take int > + * parameters even though the ioctl definition specifies long. > + * Userland has been expecting int for ages (and chattr > + * segfaults on FUSE filesystems), so special case that here. > + * The IOC32 variants were declared with int, so they don't > + * need this correction. > + */ > + switch (cmd) { > + case FS_IOC_GETFLAGS: > + case FS_IOC_SETFLAGS: > + case FS_IOC_GETVERSION: > + case FS_IOC_SETVERSION: > + iov->iov_len = sizeof(int); > + } > + > if (_IOC_DIR(cmd) & _IOC_WRITE) { > in_iov = iov; > in_iovs = 1; > > ------------------------------------------------------------------------------ > Rapidly troubleshoot problems before they affect your business. Most IT > organizations don't have a clear picture of how application performance > affects their revenue. With AppDynamics, you get 100% visibility into your > Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! > http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk > _______________________________________________ > fuse-devel mailing list > fuse-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/fuse-devel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/