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authorTrond Myklebust <trond.myklebust@hammerspace.com>2020-04-02 15:27:09 -0400
committerTrond Myklebust <trond.myklebust@hammerspace.com>2020-04-03 18:26:02 -0400
commitfc51b1cf391dd91ff9362861ed226ef51048e863 (patch)
tree4b71836ccd7b74efcd72964427ab95389654e953 /fs/nfs/delegation.c
parentf30a6ea0f3a582cea72b0373612d4b38f383fbd9 (diff)
NFS: Beware when dereferencing the delegation cred
When we look up the delegation cred, we are usually doing so in conjunction with a read of the stateid, and we want to ensure that the look up is atomic with that read. Fixes: 57f188e04773 ("NFSv4: nfs_update_inplace_delegation() should update delegation cred") [sfr@canb.auug.org.au: Fixed up borken Fixes: line from Trond :-)] Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Diffstat (limited to 'fs/nfs/delegation.c')
-rw-r--r--fs/nfs/delegation.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 01974f17afc9..816e1427f17e 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -1243,8 +1243,10 @@ restart_locked:
inode = nfs_delegation_grab_inode(delegation);
if (inode == NULL)
goto restart_locked;
+ spin_lock(&delegation->lock);
cred = get_cred_rcu(delegation->cred);
nfs4_stateid_copy(&stateid, &delegation->stateid);
+ spin_unlock(&delegation->lock);
clear_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags);
rcu_read_unlock();
nfs_delegation_test_free_expired(inode, &stateid, cred);
@@ -1363,11 +1365,14 @@ bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags,
{
struct nfs_inode *nfsi = NFS_I(inode);
struct nfs_delegation *delegation;
- bool ret;
+ bool ret = false;
flags &= FMODE_READ|FMODE_WRITE;
rcu_read_lock();
delegation = rcu_dereference(nfsi->delegation);
+ if (!delegation)
+ goto out;
+ spin_lock(&delegation->lock);
ret = nfs4_is_valid_delegation(delegation, flags);
if (ret) {
nfs4_stateid_copy(dst, &delegation->stateid);
@@ -1375,6 +1380,8 @@ bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags,
if (cred)
*cred = get_cred(delegation->cred);
}
+ spin_unlock(&delegation->lock);
+out:
rcu_read_unlock();
return ret;
}