From: "J. Bruce Fields" <bfields@fieldses.org>
To: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Al Viro <viro@zeniv.linux.org.uk>,
Alexey Dobriyan <adobriyan@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Pavel Emelyanov <xemul@parallels.com>,
James Bottomley <jbottomley@parallels.com>,
Matthew Helsley <matt.helsley@gmail.com>,
aneesh.kumar@linux.vnet.ibm.com
Subject: Re: [patch 4/9] fs, exportfs: Fix nil dereference if no s_export_op present
Date: Thu, 23 Aug 2012 11:22:01 -0400 [thread overview]
Message-ID: <20120823152201.GB6923@fieldses.org> (raw)
In-Reply-To: <20120823123422.GB9112@moon>
On Thu, Aug 23, 2012 at 04:34:22PM +0400, Cyrill Gorcunov wrote:
> On Thu, Aug 23, 2012 at 08:12:30AM -0400, J. Bruce Fields wrote:
> > On Thu, Aug 23, 2012 at 02:43:27PM +0400, Cyrill Gorcunov wrote:
> > > If there is no s_export_op present in a target superblock
> > > we might have nil dereference.
> >
> > Is that NULL dereference possible with current code, or is it a check
> > you're adding to account for a new caller that you're about to add?
> >
> > I believe it's the latter, but this would be a good thing to make clear
> > in the changelog.
>
> With the current code it seems to be impossible (well, i can't be sure
> about nfs caller) because do_sys_name_to_handle does check for s_export_op
> to exist. Updated changelog below. After all I think not checking
> s_export_op was a mistake in general -- this routine is exported to
> other modules but has no a single line of comment about possibility
> of nil dereference.
Fine, just make sure that's explained in the changelog.
For distributors looking for patches to backport, "fix nil dereference"
may set off alarm bells unnecessarily.
--b.
> ---
> From: Cyrill Gorcunov <gorcunov@openvz.org>
> Subject: fs, exportfs: Escape nil dereference if no s_export_op present
>
> This routine will be used to generate a file handle in fdinfo
> output for inotify subsystem, where if no s_export_op present
> the general export_encode_fh should be used. Thus add
> a test if s_export_op present inside exportfs_encode_fh itself.
>
> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
> CC: Pavel Emelyanov <xemul@parallels.com>
> CC: Al Viro <viro@ZenIV.linux.org.uk>
> CC: Alexey Dobriyan <adobriyan@gmail.com>
> CC: Andrew Morton <akpm@linux-foundation.org>
> CC: James Bottomley <jbottomley@parallels.com>
> CC: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
> CC: Alexey Dobriyan <adobriyan@gmail.com>
> CC: Matthew Helsley <matt.helsley@gmail.com>
> CC: "J. Bruce Fields" <bfields@fieldses.org>
> CC: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
> ---
> fs/exportfs/expfs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Index: linux-2.6.git/fs/exportfs/expfs.c
> ===================================================================
> --- linux-2.6.git.orig/fs/exportfs/expfs.c
> +++ linux-2.6.git/fs/exportfs/expfs.c
> @@ -357,7 +357,7 @@ int exportfs_encode_fh(struct dentry *de
> */
> parent = p->d_inode;
> }
> - if (nop->encode_fh)
> + if (nop && nop->encode_fh)
> error = nop->encode_fh(inode, fid->raw, max_len, parent);
> else
> error = export_encode_fh(inode, fid, max_len, parent);
> --
> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
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> More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2012-08-23 15:22 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-23 10:43 [patch 0/9] extended fdinfo via procfs series, v7 Cyrill Gorcunov
2012-08-23 10:43 ` [patch 1/9] procfs: Move /proc/pid/fd[info] handling code to fd.[ch] Cyrill Gorcunov
2012-08-25 17:16 ` Al Viro
2012-08-25 17:39 ` Cyrill Gorcunov
2012-08-25 17:55 ` Al Viro
2012-08-25 18:58 ` Cyrill Gorcunov
2012-08-25 19:12 ` Al Viro
2012-08-25 19:43 ` Cyrill Gorcunov
2012-08-25 21:52 ` Al Viro
2012-08-25 23:19 ` Al Viro
2012-08-23 10:43 ` [patch 2/9] procfs: Convert /proc/pid/fdinfo/ handling routines to seq-file v2 Cyrill Gorcunov
2012-08-26 2:46 ` Al Viro
2012-08-26 8:13 ` Cyrill Gorcunov
2012-08-26 14:28 ` Cyrill Gorcunov
2012-08-26 15:05 ` Al Viro
2012-08-26 15:10 ` Cyrill Gorcunov
2012-08-23 10:43 ` [patch 3/9] procfs: Add ability to plug in auxiliary fdinfo providers Cyrill Gorcunov
2012-08-23 10:43 ` [patch 4/9] fs, exportfs: Fix nil dereference if no s_export_op present Cyrill Gorcunov
2012-08-23 12:12 ` J. Bruce Fields
2012-08-23 12:34 ` Cyrill Gorcunov
2012-08-23 15:22 ` J. Bruce Fields [this message]
2012-08-23 10:43 ` [patch 5/9] fs, notify: Add file handle entry into inotify_inode_mark Cyrill Gorcunov
2012-08-23 10:43 ` [patch 6/9] fs, notify: Add procfs fdinfo helper v4 Cyrill Gorcunov
2012-08-23 10:43 ` [patch 7/9] fs, eventfd: Add procfs fdinfo helper Cyrill Gorcunov
2012-08-23 10:43 ` [patch 8/9] fs, epoll: Add procfs fdinfo helper v2 Cyrill Gorcunov
2012-08-23 10:43 ` [patch 9/9] fdinfo: Show sigmask for signalfd fd v2 Cyrill Gorcunov
2012-08-23 12:23 ` [patch 0/9] extended fdinfo via procfs series, v7 J. Bruce Fields
2012-08-23 12:44 ` Cyrill Gorcunov
2012-08-23 13:52 ` J. Bruce Fields
2012-08-23 13:56 ` Cyrill Gorcunov
2012-08-23 15:25 ` J. Bruce Fields
2012-08-23 17:02 ` Cyrill Gorcunov
2012-08-23 17:59 ` J. Bruce Fields
2012-08-23 18:03 ` Cyrill Gorcunov
2012-08-23 17:28 ` Cyrill Gorcunov
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