[PATCH AUTOSEL 5.4 108/330] ceph: ensure we have a new cap before continuing in fill_inode

[PATCH AUTOSEL 5.4 108/330] ceph: ensure we have a new cap before continuing in fill_inode

[Sasha Levin]

From: Jeff Layton <jlayton@kernel.org>

[ Upstream commit 9a6bed4fe0c8bf57785cbc4db9f86086cb9b193d ]

If the caller passes in a NULL cap_reservation, and we can't allocate
one then ensure that we fail gracefully.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ceph/inode.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index c07407586ce87..660a878e20ef2 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -754,8 +754,11 @@ static int fill_inode(struct inode *inode, struct page *locked_page,
 	info_caps = le32_to_cpu(info->cap.caps);
 
 	/* prealloc new cap struct */
-	if (info_caps && ceph_snap(inode) == CEPH_NOSNAP)
+	if (info_caps && ceph_snap(inode) == CEPH_NOSNAP) {
 		new_cap = ceph_get_cap(mdsc, caps_reservation);
+		if (!new_cap)
+			return -ENOMEM;
+	}
 
 	/*
 	 * prealloc xattr data, if it looks like we'll need it.  only
-- 
2.25.1

[PATCH AUTOSEL 5.4 305/330] ceph: fix potential race in ceph_check_caps

[Sasha Levin]

From: Jeff Layton <jlayton@kernel.org>

[ Upstream commit dc3da0461cc4b76f2d0c5b12247fcb3b520edbbf ]

Nothing ensures that session will still be valid by the time we
dereference the pointer. Take and put a reference.

In principle, we should always be able to get a reference here, but
throw a warning if that's ever not the case.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ceph/caps.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index b2695919435e8..af563d73d252c 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2013,12 +2013,24 @@ ack:
 			if (mutex_trylock(&session->s_mutex) == 0) {
 				dout("inverting session/ino locks on %p\n",
 				     session);
+				session = ceph_get_mds_session(session);
 				spin_unlock(&ci->i_ceph_lock);
 				if (took_snap_rwsem) {
 					up_read(&mdsc->snap_rwsem);
 					took_snap_rwsem = 0;
 				}
-				mutex_lock(&session->s_mutex);
+				if (session) {
+					mutex_lock(&session->s_mutex);
+					ceph_put_mds_session(session);
+				} else {
+					/*
+					 * Because we take the reference while
+					 * holding the i_ceph_lock, it should
+					 * never be NULL. Throw a warning if it
+					 * ever is.
+					 */
+					WARN_ON_ONCE(true);
+				}
 				goto retry;
 			}
 		}
-- 
2.25.1