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@xxxxxxxxxx> > 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@xxxxxxxxxx> > CC: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> > CC: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > CC: Alexey Dobriyan <adobriyan@xxxxxxxxx> > CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > CC: James Bottomley <jbottomley@xxxxxxxxxxxxx> > CC: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> > CC: Alexey Dobriyan <adobriyan@xxxxxxxxx> > CC: Matthew Helsley <matt.helsley@xxxxxxxxx> > CC: "J. Bruce Fields" <bfields@xxxxxxxxxxxx> > CC: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> > --- > 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 > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
