[PATCH 4.19 069/118] ceph: quota: fix null pointer dereference in quota check

Greg Kroah-Hartman
2018-11-26T11:04:29Z

[ Upstream commit 71f2cc64d027d712f29bf8d09d3e123302d5f245 ]

This patch fixes a possible null pointer dereference in
check_quota_exceeded, detected by the static checker smatch, with the
following warning:

fs/ceph/quota.c:240 check_quota_exceeded()
error: we previously assumed 'realm' could be null (see line 188)

Fixes: b7a2921765cf ("ceph: quota: support for ceph.quota.max_files")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ceph/quota.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c
index 32d4f13784ba..03f4d24db8fe 100644
--- a/fs/ceph/quota.c
+++ b/fs/ceph/quota.c
@@ -237,7 +237,8 @@ static bool check_quota_exceeded(struct inode *inode, enum quota_check_op op,
ceph_put_snap_realm(mdsc, realm);
realm = next;
}
- ceph_put_snap_realm(mdsc, realm);
+ if (realm)
+ ceph_put_snap_realm(mdsc, realm);
up_read(&mdsc->snap_rwsem);

return exceeded;
--
2.17.1