From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Whitehouse Date: Tue, 12 Nov 2013 12:35:12 +0000 Subject: [Cluster-devel] [PATCH] gfs2: fix potential NULL pointer dereference In-Reply-To: <1384259405-7913-1-git-send-email-mpn@google.com> References: <1384259405-7913-1-git-send-email-mpn@google.com> Message-ID: <1384259712.2697.9.camel@menhir> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi, Yes, good catch. Thanks, I'll add it to the tree, Steve. On Tue, 2013-11-12 at 13:30 +0100, Michal Nazarewicz wrote: > From: Michal Nazarewicz > > Commit [e66cf1610: GFS2: Use lockref for glocks] replaced call: > atomic_read(&gi->gl->gl_ref) == 0 > with: > __lockref_is_dead(&gl->gl_lockref) > therefore changing how gl is accessed, from gi->gl to plan gl. > However, gl can be a NULL pointer, and so gi->gl needs to be > used instead (which is guaranteed not to be NULL because fo > the while loop checking that condition). > > Signed-off-by: Michal Nazarewicz > --- > fs/gfs2/glock.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c > index e66a800..c8420f7 100644 > --- a/fs/gfs2/glock.c > +++ b/fs/gfs2/glock.c > @@ -1899,7 +1899,8 @@ static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi) > gi->nhash = 0; > } > /* Skip entries for other sb and dead entries */ > - } while (gi->sdp != gi->gl->gl_sbd || __lockref_is_dead(&gl->gl_lockref)); > + } while (gi->sdp != gi->gl->gl_sbd || > + __lockref_is_dead(&gi->gl->gl_lockref)); > > return 0; > }