On Thu, Apr 14, 2022 at 11:33 PM Shyam Prasad N <nspmangalore@xxxxxxxxx> wrote:
>
> On Wed, Apr 13, 2022 at 7:06 AM Ronnie Sahlberg <lsahlber@xxxxxxxxxx> wrote:
> >
> > On umount, cifs_sb->tlink_tree might contain entries that do not represent
> > a valid tcon.
> > Check the tcon for error before we dereference it.
> >
> > Signed-off-by: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>
> > ---
> > fs/cifs/cifsfs.c | 6 +++---
> > 1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> > index aba0783a8f09..25719b70564a 100644
> > --- a/fs/cifs/cifsfs.c
> > +++ b/fs/cifs/cifsfs.c
> > @@ -266,10 +266,11 @@ static void cifs_kill_sb(struct super_block *sb)
> > * before we kill the sb.
> > */
> > if (cifs_sb->root) {
> > - node = rb_first(root);
> > - while (node != NULL) {
> > + for(node = rb_first(root); node; node = rb_next(node)) {
> > tlink = rb_entry(node, struct tcon_link, tl_rbnode);
> > tcon = tlink_tcon(tlink);
> > + if (IS_ERR(tcon))
> > + continue;
> > cfid = &tcon->crfid;
> > mutex_lock(&cfid->fid_mutex);
> > if (cfid->dentry) {
> > @@ -277,7 +278,6 @@ static void cifs_kill_sb(struct super_block *sb)
> > cfid->dentry = NULL;
> > }
> > mutex_unlock(&cfid->fid_mutex);
> > - node = rb_next(node);
> > }
> >
> > /* finally release root dentry */
> > --
> > 2.30.2
> >
>
> The changes look good to me.
> Reviewed-by: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
>
> Does this cover all the mount failure scenarios, Ronnie?
It should. It should also fix similar issues at umount if an idle tcon
has been reaped, or say a tcon failed to initialize during multiuser.
For example, mount multiuser, then try to access the share with a
different user without credentials. That second tcon will fail
and then when we umount we would oops.
>
> --
> Regards,
> Shyam
