[PATCH AUTOSEL 6.1 22/27] ceph: fix invalid pointer access if get_quota_realm return ERR_PTR

Sasha Levin
2024-01-28T16:15:02Z

From: Wenchao Hao <haowenchao2@huawei.com>

[ Upstream commit 0f4cf64eabc6e16cfc2704f1960e82dc79d91c8d ]

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.

[ xiubli: minor code style clean up ]

Signed-off-by: Wenchao Hao <haowenchao2@huawei.com>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 f7fcf7f08ec6..ca4932e6f71b 100644
--- a/fs/ceph/quota.c
+++ b/fs/ceph/quota.c
@@ -194,10 +194,10 @@ 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.
@@ -208,18 +208,19 @@ 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_inode_info *ci = NULL;
struct ceph_snap_realm *realm, *next;
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;
@@ -245,7 +246,7 @@ 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;
}

@@ -254,8 +255,11 @@ 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);
@@ -264,7 +268,7 @@ 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)
@@ -272,6 +276,7 @@ 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:
/*
@@ -281,9 +286,9 @@ 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);
@@ -485,8 +490,8 @@ 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);
up_read(&mdsc->snap_rwsem);
if (!realm)
return false;
--
2.43.0