From 113aac6d567bda783af36d08f73bfda47d8e9a40 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Sun, 10 Jan 2021 15:46:06 -0500 Subject: [PATCH] NFS: nfs_delegation_find_inode_server must first reference the superblock Before referencing the inode, we must ensure that the superblock can be referenced. Otherwise, we can end up with iput() calling superblock operations that are no longer valid or accessible. Fixes: e39d8a186ed0 ("NFSv4: Fix an Oops during delegation callbacks") Signed-off-by: Trond Myklebust --- fs/nfs/delegation.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c index 816e1427f17e..04bf8066980c 100644 --- a/fs/nfs/delegation.c +++ b/fs/nfs/delegation.c @@ -1011,22 +1011,24 @@ nfs_delegation_find_inode_server(struct nfs_server *server, const struct nfs_fh *fhandle) { struct nfs_delegation *delegation; - struct inode *freeme, *res = NULL; + struct super_block *freeme = NULL; + struct inode *res = NULL; list_for_each_entry_rcu(delegation, &server->delegations, super_list) { spin_lock(&delegation->lock); if (delegation->inode != NULL && !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) && nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) { - freeme = igrab(delegation->inode); - if (freeme && nfs_sb_active(freeme->i_sb)) - res = freeme; + if (nfs_sb_active(server->super)) { + freeme = server->super; + res = igrab(delegation->inode); + } spin_unlock(&delegation->lock); if (res != NULL) return res; if (freeme) { rcu_read_unlock(); - iput(freeme); + nfs_sb_deactive(freeme); rcu_read_lock(); } return ERR_PTR(-EAGAIN);