2020-02-13 19:56:25

by Trond Myklebust

[permalink] [raw]
Subject: [PATCH 2/2] NFSv4: Ensure the delegation cred is pinned when we call delegreturn

Ensure we don't release the delegation cred during the call to
nfs4_proc_delegreturn().

Fixes: ee05f456772d ("NFSv4: Fix races between open and delegreturn")
Signed-off-by: Trond Myklebust <[email protected]>
---
fs/nfs/delegation.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index c17ff826e7e9..1865322de142 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -255,13 +255,18 @@ void nfs_inode_reclaim_delegation(struct inode *inode, const struct cred *cred,

static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
{
+ const struct cred *cred;
int res = 0;

- if (!test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
- res = nfs4_proc_delegreturn(inode,
- delegation->cred,
+ if (!test_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
+ spin_lock(&delegation->lock);
+ cred = get_cred(delegation->cred);
+ spin_unlock(&delegation->lock);
+ res = nfs4_proc_delegreturn(inode, cred,
&delegation->stateid,
issync);
+ put_cred(cred);
+ }
return res;
}

--
2.24.1