From: Trond Myklebust <trond.myklebust@hammerspace.com> mainline inclusion from mainline-v5.7-rc1 commit 75da98586af75eb80664714a67a9895bf0a5517e category: bugfix bugzilla: NA CVE: NA -------------------------------- We must not return from nfs_d_automount() without holding 2 references to the mount record. Doing so, will trigger the BUG() in finish_automount(). Also ensure that we don't try to reschedule the automount timer with a negative or zero timeout value. Fixes: 22a1ae9a93fb ("NFS: If nfs_mountpoint_expiry_timeout < 0, do not expire submounts") Cc: stable@vger.kernel.org # v5.5+ Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> Conflicts: fs/nfs/namespace.c Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- fs/nfs/namespace.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c index b7cac07fe0c80..30a230fde3315 100644 --- a/fs/nfs/namespace.c +++ b/fs/nfs/namespace.c @@ -146,6 +146,7 @@ struct vfsmount *nfs_d_automount(struct path *path) struct nfs_server *server = NFS_SERVER(d_inode(path->dentry)); struct nfs_fh *fh = NULL; struct nfs_fattr *fattr = NULL; + int timeout = READ_ONCE(nfs_mountpoint_expiry_timeout); if (IS_ROOT(path->dentry)) return ERR_PTR(-ESTALE); @@ -160,12 +161,12 @@ struct vfsmount *nfs_d_automount(struct path *path) if (IS_ERR(mnt)) goto out; - if (nfs_mountpoint_expiry_timeout < 0) + mntget(mnt); /* prevent immediate expiration */ + if (timeout <= 0) goto out; - mntget(mnt); /* prevent immediate expiration */ mnt_set_expiry(mnt, &nfs_automount_list); - schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); + schedule_delayed_work(&nfs_automount_task, timeout); out: nfs_free_fattr(fattr); @@ -204,10 +205,11 @@ const struct inode_operations nfs_referral_inode_operations = { static void nfs_expire_automounts(struct work_struct *work) { struct list_head *list = &nfs_automount_list; + int timeout = READ_ONCE(nfs_mountpoint_expiry_timeout); mark_mounts_for_expiry(list); - if (!list_empty(list)) - schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); + if (!list_empty(list) && timeout > 0) + schedule_delayed_work(&nfs_automount_task, timeout); } void nfs_release_automount_timer(void) -- 2.25.1