1 files changed, 21 insertions, 4 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index f2b92f6a7efb..9d992b0346e3 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -4519,6 +4519,25 @@ int nfs4_proc_fs_locations(struct inode *dir, const struct qstr *name,
 
 #ifdef CONFIG_NFS_V4_1
 /*
+ * Check the exchange flags returned by the server for invalid flags, having
+ * both PNFS and NON_PNFS flags set, and not having one of NON_PNFS, PNFS, or
+ * DS flags set.
+ */
+static int nfs4_check_cl_exchange_flags(u32 flags)
+{
+        if (flags & ~EXCHGID4_FLAG_MASK_R)
+                goto out_inval;
+        if ((flags & EXCHGID4_FLAG_USE_PNFS_MDS) &&
+            (flags & EXCHGID4_FLAG_USE_NON_PNFS))
+                goto out_inval;
+        if (!(flags & (EXCHGID4_FLAG_MASK_PNFS)))
+                goto out_inval;
+        return NFS_OK;
+out_inval:
+        return -NFS4ERR_INVAL;
+}
+
+/*
  * nfs4_proc_exchange_id()
  *
  * Since the clientid has expired, all compounds using sessions
@@ -4531,7 +4550,7 @@ int nfs4_proc_exchange_id(struct nfs_client *clp, struct rpc_cred *cred)
         nfs4_verifier verifier;
         struct nfs41_exchange_id_args args = {
                 .client = clp,
-                .flags = clp->cl_exchange_flags,
+                .flags = EXCHGID4_FLAG_SUPP_MOVED_REFER,
         };
         struct nfs41_exchange_id_res res = {
                 .client = clp,
@@ -4548,9 +4567,6 @@ int nfs4_proc_exchange_id(struct nfs_client *clp, struct rpc_cred *cred)
         dprintk("--> %s\n", __func__);
         BUG_ON(clp == NULL);
 
-        /* Remove server-only flags */
-        args.flags &= ~EXCHGID4_FLAG_CONFIRMED_R;
-
         p = (u32 *)verifier.data;
         *p++ = htonl((u32)clp->cl_boot_time.tv_sec);
         *p = htonl((u32)clp->cl_boot_time.tv_nsec);
@@ -4576,6 +4592,7 @@ int nfs4_proc_exchange_id(struct nfs_client *clp, struct rpc_cred *cred)
                         break;
         }
 
+        status = nfs4_check_cl_exchange_flags(clp->cl_exchange_flags);
         dprintk("<-- %s status= %d\n", __func__, status);
         return status;
 }