This issue is reported by smatch that get_quota_realm() might return
ERR_PTR but we did not handle it. It's not a immediate bug, while we
still should address it to avoid potential bugs if get_quota_realm()
is changed to return other ERR_PTR in future.
Set ceph_snap_realm's pointer in get_quota_realm()'s to address this
issue, the pointer would be set to NULL if get_quota_realm() failed
to get struct ceph_snap_realm, so no ERR_PTR would happen any more.
Signed-off-by: Wenchao Hao <haowenchao2@xxxxxxxxxx>
---
V3:
- Remove redundant variable initialization in ceph_quota_is_same_realm
V2:
- Fix all potential invalid pointer access caused by get_quota_realm
- Update commit comment and point it's not a immediate bug
fs/ceph/quota.c | 39 ++++++++++++++++++++++-----------------
1 file changed, 22 insertions(+), 17 deletions(-)
diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c
index 9d36c3532de1..b25906a5bfbb 100644
--- a/fs/ceph/quota.c
+++ b/fs/ceph/quota.c
@@ -197,10 +197,10 @@ void ceph_cleanup_quotarealms_inodes(struct ceph_mds_client *mdsc)
}
/*
- * This function walks through the snaprealm for an inode and returns the
- * ceph_snap_realm for the first snaprealm that has quotas set (max_files,
+ * This function walks through the snaprealm for an inode and set the
+ * realmp with the first snaprealm that has quotas set (max_files,
* max_bytes, or any, depending on the 'which_quota' argument). If the root is
- * reached, return the root ceph_snap_realm instead.
+ * reached, set the realmp with the root ceph_snap_realm instead.
*
* Note that the caller is responsible for calling ceph_put_snap_realm() on the
* returned realm.
@@ -211,10 +211,9 @@ void ceph_cleanup_quotarealms_inodes(struct ceph_mds_client *mdsc)
* this function will return -EAGAIN; otherwise, the snaprealms walk-through
* will be restarted.
*/
-static struct ceph_snap_realm *get_quota_realm(struct ceph_mds_client *mdsc,
- struct inode *inode,
- enum quota_get_realm which_quota,
- bool retry)
+static int get_quota_realm(struct ceph_mds_client *mdsc, struct inode *inode,
+ enum quota_get_realm which_quota,
+ struct ceph_snap_realm **realmp, bool retry)
{
struct ceph_client *cl = mdsc->fsc->client;
struct ceph_inode_info *ci = NULL;
@@ -222,8 +221,10 @@ static struct ceph_snap_realm *get_quota_realm(struct ceph_mds_client *mdsc,
struct inode *in;
bool has_quota;
+ if (realmp)
+ *realmp = NULL;
if (ceph_snap(inode) != CEPH_NOSNAP)
- return NULL;
+ return 0;
restart:
realm = ceph_inode(inode)->i_snap_realm;
@@ -250,7 +251,7 @@ static struct ceph_snap_realm *get_quota_realm(struct ceph_mds_client *mdsc,
break;
ceph_put_snap_realm(mdsc, realm);
if (!retry)
- return ERR_PTR(-EAGAIN);
+ return -EAGAIN;
goto restart;
}
@@ -259,8 +260,11 @@ static struct ceph_snap_realm *get_quota_realm(struct ceph_mds_client *mdsc,
iput(in);
next = realm->parent;
- if (has_quota || !next)
- return realm;
+ if (has_quota || !next) {
+ if (realmp)
+ *realmp = realm;
+ return 0;
+ }
ceph_get_snap_realm(mdsc, next);
ceph_put_snap_realm(mdsc, realm);
@@ -269,7 +273,7 @@ static struct ceph_snap_realm *get_quota_realm(struct ceph_mds_client *mdsc,
if (realm)
ceph_put_snap_realm(mdsc, realm);
- return NULL;
+ return 0;
}
bool ceph_quota_is_same_realm(struct inode *old, struct inode *new)
@@ -277,6 +281,7 @@ bool ceph_quota_is_same_realm(struct inode *old, struct inode *new)
struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(old->i_sb);
struct ceph_snap_realm *old_realm, *new_realm;
bool is_same;
+ int ret;
restart:
/*
@@ -286,9 +291,9 @@ bool ceph_quota_is_same_realm(struct inode *old, struct inode *new)
* dropped and we can then restart the whole operation.
*/
down_read(&mdsc->snap_rwsem);
- old_realm = get_quota_realm(mdsc, old, QUOTA_GET_ANY, true);
- new_realm = get_quota_realm(mdsc, new, QUOTA_GET_ANY, false);
- if (PTR_ERR(new_realm) == -EAGAIN) {
+ get_quota_realm(mdsc, old, QUOTA_GET_ANY, &old_realm, true);
+ ret = get_quota_realm(mdsc, new, QUOTA_GET_ANY, &new_realm, false);
+ if (ret == -EAGAIN) {
up_read(&mdsc->snap_rwsem);
if (old_realm)
ceph_put_snap_realm(mdsc, old_realm);
@@ -492,8 +497,8 @@ bool ceph_quota_update_statfs(struct ceph_fs_client *fsc, struct kstatfs *buf)
bool is_updated = false;
down_read(&mdsc->snap_rwsem);
- realm = get_quota_realm(mdsc, d_inode(fsc->sb->s_root),
- QUOTA_GET_MAX_BYTES, true);
+ get_quota_realm(mdsc, d_inode(fsc->sb->s_root),
+ QUOTA_GET_MAX_BYTES, &realm, true);
