From: Miklos Szeredi <miklos@szeredi.hu>
To: Greg Kurz <groug@kaod.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
virtualization@lists.linux-foundation.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
virtio-fs-list <virtio-fs@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
Max Reitz <mreitz@redhat.com>, Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [PATCH v4 1/5] fuse: Fix leak in fuse_dentry_automount() error path
Date: Fri, 21 May 2021 10:23:47 +0200 [thread overview]
Message-ID: <CAJfpegt8JS-9LsRhmw9W2VMNG+tc+gGNsSwy1ULLoSFeYpHueA@mail.gmail.com> (raw)
In-Reply-To: <20210521101523.4f276dac@bahia.lan>
On Fri, 21 May 2021 at 10:15, Greg Kurz <groug@kaod.org> wrote:
>
> On Fri, 21 May 2021 09:54:19 +0200
> Miklos Szeredi <miklos@szeredi.hu> wrote:
>
> > On Thu, 20 May 2021 at 21:45, Al Viro <viro@zeniv.linux.org.uk> wrote:
> > >
> > > On Thu, May 20, 2021 at 05:46:50PM +0200, Greg Kurz wrote:
> > > > Some rollback was forgotten during the addition of crossmounts.
> > >
> > > Have you actually tested that? Because I strongly suspect that
> > > by that point the ownership of fc and fm is with sb and those
> > > should be taken care of by deactivate_locked_super().
> >
> > Not quite. Patch looks correct because destruction of fm is done in
> > fuse_put_super(), which only gets called if the sb initialization gets
> > as far as setting up sb->s_root, which only happens after the
> > successful fuse_fill_super_submount() call in this case.
> >
> > Doing the destruction from the various ->kill_sb() instances instead
> > of from ->put_super() would also fix this, but I'm not quite sure that
> > that would be any cleaner.
> >
>
> As saying in the answer I've just posted, a failure in
> fuse_fill_super_submount() causes an actual crash because
> fuse_mount_remove() logically assumes fm to already be in
> fc->mounts, which isn't the case at this point.
>
> In the root mount case, this is handled by taking back
> the ownership on fm, i.e. do the rollback *and* clear
> sb->s_fs_info. It seems that the same should be done
> for submounts.
Agreed. Thanks for verifying.
Miklos
next prev parent reply other threads:[~2021-05-21 8:24 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-20 15:46 [PATCH v4 0/5] virtiofs: propagate sync() to file server Greg Kurz
2021-05-20 15:46 ` [PATCH v4 1/5] fuse: Fix leak in fuse_dentry_automount() error path Greg Kurz
2021-05-20 19:45 ` Al Viro
2021-05-21 7:54 ` Miklos Szeredi
2021-05-21 8:15 ` Greg Kurz
2021-05-21 8:23 ` Miklos Szeredi [this message]
2021-05-21 8:08 ` Greg Kurz
2021-05-20 15:46 ` [PATCH v4 2/5] fuse: Call vfs_get_tree() for submounts Greg Kurz
2021-05-21 8:19 ` Miklos Szeredi
2021-05-21 8:28 ` Greg Kurz
2021-05-22 17:50 ` kernel test robot
2021-05-22 20:12 ` kernel test robot
2021-05-20 15:46 ` [PATCH v4 3/5] fuse: Make fuse_fill_super_submount() static Greg Kurz
2021-05-20 15:46 ` [PATCH v4 4/5] virtiofs: Skip submounts in sget_fc() Greg Kurz
2021-05-21 8:26 ` Miklos Szeredi
2021-05-21 8:39 ` Greg Kurz
2021-05-21 8:50 ` Miklos Szeredi
2021-05-21 10:06 ` Greg Kurz
2021-05-21 12:37 ` Miklos Szeredi
2021-05-21 13:36 ` Greg Kurz
2021-05-20 15:46 ` [PATCH v4 5/5] virtiofs: propagate sync() to file server Greg Kurz
2021-05-21 10:08 ` Greg Kurz
2021-05-21 12:51 ` Miklos Szeredi
2021-08-15 14:14 ` Amir Goldstein
2021-08-16 15:29 ` Vivek Goyal
2021-08-16 18:57 ` Amir Goldstein
2021-08-16 19:11 ` Vivek Goyal
2021-08-16 19:46 ` Amir Goldstein
2021-08-28 15:21 ` Miklos Szeredi
2021-08-30 17:01 ` Vivek Goyal
2021-08-30 17:36 ` Miklos Szeredi
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