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Message-ID: <748532c2-9382-0a3c-8acd-c8261f741174@redhat.com>
Date: Thu, 23 Nov 2023 10:25:18 +0800
From: Xiubo Li <xiubli@...hat.com>
To: Wenchao Hao <haowenchao2@...wei.com>,
Ilya Dryomov <idryomov@...il.com>,
Jeff Layton <jlayton@...nel.org>,
Luis Henriques <lhenriques@...e.de>, ceph-devel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] ceph: quota: Fix invalid pointer access if
get_quota_realm return ERR_PTR
On 11/23/23 09:53, Wenchao Hao wrote:
> 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@...wei.com>
> ---
> 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);
Some extra white spaces here.
Otherwise LGTM.
I will adjust it and applying it to the testing branch.
Thanks
- Xiubo
> up_read(&mdsc->snap_rwsem);
> if (!realm)
> return false;
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