nfsd: Detect unhashed stids in nfsd4_verify_open_stid()

Web:        https://git.kernel.org/torvalds/c/4f1764172a0aa7395d12b96cae640ca1438c5085
Commit:     4f1764172a0aa7395d12b96cae640ca1438c5085
Parent:     d0945caafcccac9d8f4d78f99e0eac9e60386381
Refname:    refs/heads/master
Author:     Trond Myklebust <[email protected]>
AuthorDate: Fri Jan 12 17:42:30 2018 -0500
Committer:  J. Bruce Fields <[email protected]>
CommitDate: Mon Feb 5 17:13:16 2018 -0500

    nfsd: Detect unhashed stids in nfsd4_verify_open_stid()
    
    The state of the stid is guaranteed by 2 locks:
    - The nfs4_client 'cl_lock' spinlock
    - The nfs4_ol_stateid 'st_mutex' mutex
    
    so it is quite possible for the stid to be unhashed after lookup,
    but before calling nfsd4_lock_ol_stateid(). So we do need to check
    for a zero value for 'sc_type' in nfsd4_verify_open_stid().
    
    Signed-off-by: Trond Myklebust <[email protected]>
    Tested-by: Checuk Lever <[email protected]>
    Cc: [email protected]
    Fixes: 659aefb68eca "nfsd: Ensure we don't recognise lock stateids..."
    Signed-off-by: J. Bruce Fields <[email protected]>
---
 fs/nfsd/nfs4state.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index b29b5a185a2c..5a75135f5f53 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -3590,6 +3590,7 @@ nfsd4_verify_open_stid(struct nfs4_stid *s)
 	switch (s->sc_type) {
 	default:
 		break;
+	case 0:
 	case NFS4_CLOSED_STID:
 	case NFS4_CLOSED_DELEG_STID:
 		ret = nfserr_bad_stateid;
--
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