NFS: Fix nfs4_verifier memory alignment

Clean up due to code review.

The nfs4_verifier's data field is not guaranteed to be u32-aligned.
Casting an array of chars to a u32 * is considered generally
hazardous.

Fix this by using a __be32 array to generate a verifier's contents,
and then byte-copy the contents into the verifier field.  The contents
of a verifier, for all intents and purposes, are opaque bytes.  Only
local code that generates a verifier need know the actual content and
format.  Everyone else compares the full byte array for exact
equality.

Also, sizeof(nfs4_verifer) is the size of the in-core verifier data
structure, but NFS4_VERIFIER_SIZE is the number of octets in an XDR'd
verifier.  The two are not interchangeable, even if they happen to
have the same value.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 19 insertions, 13 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index e0e35288361c..1ec05222ccbc 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -836,13 +836,15 @@ static struct nfs4_opendata *nfs4_opendata_alloc(struct dentry *dentry,
         p->o_arg.dir_bitmask = server->cache_consistency_bitmask;
         p->o_arg.claim = NFS4_OPEN_CLAIM_NULL;
         if (attrs != NULL && attrs->ia_valid != 0) {
-                u32 *s;
+                __be32 verf[2];
 
                 p->o_arg.u.attrs = &p->attrs;
                 memcpy(&p->attrs, attrs, sizeof(p->attrs));
-                s = (u32 *) p->o_arg.u.verifier.data;
-                s[0] = jiffies;
-                s[1] = current->pid;
+
+                verf[0] = jiffies;
+                verf[1] = current->pid;
+                memcpy(p->o_arg.u.verifier.data, verf,
+                                sizeof(p->o_arg.u.verifier.data));
         }
         p->c_arg.fh = &p->o_res.fh;
         p->c_arg.stateid = &p->o_res.stateid;
@@ -3819,6 +3821,16 @@ wait_on_recovery:
         return -EAGAIN;
 }
 
+static void nfs4_construct_boot_verifier(struct nfs_client *clp,
+                                         nfs4_verifier *bootverf)
+{
+        __be32 verf[2];
+
+        verf[0] = htonl((u32)clp->cl_boot_time.tv_sec);
+        verf[1] = htonl((u32)clp->cl_boot_time.tv_nsec);
+        memcpy(bootverf->data, verf, sizeof(bootverf->data));
+}
+
 int nfs4_proc_setclientid(struct nfs_client *clp, u32 program,
                 unsigned short port, struct rpc_cred *cred,
                 struct nfs4_setclientid_res *res)
@@ -3835,13 +3847,10 @@ int nfs4_proc_setclientid(struct nfs_client *clp, u32 program,
                 .rpc_resp = res,
                 .rpc_cred = cred,
         };
-        __be32 *p;
         int loop = 0;
         int status;
 
-        p = (__be32*)sc_verifier.data;
-        *p++ = htonl((u32)clp->cl_boot_time.tv_sec);
-        *p = htonl((u32)clp->cl_boot_time.tv_nsec);
+        nfs4_construct_boot_verifier(clp, &sc_verifier);
 
         for(;;) {
                 rcu_read_lock();
@@ -4933,6 +4942,7 @@ int nfs4_proc_exchange_id(struct nfs_client *clp, struct rpc_cred *cred)
 {
         nfs4_verifier verifier;
         struct nfs41_exchange_id_args args = {
+                .verifier = &verifier,
                 .client = clp,
                 .flags = EXCHGID4_FLAG_SUPP_MOVED_REFER,
         };
@@ -4946,15 +4956,11 @@ int nfs4_proc_exchange_id(struct nfs_client *clp, struct rpc_cred *cred)
                 .rpc_resp = &res,
                 .rpc_cred = cred,
         };
-        __be32 *p;
 
         dprintk("--> %s\n", __func__);
         BUG_ON(clp == NULL);
 
-        p = (u32 *)verifier.data;
-        *p++ = htonl((u32)clp->cl_boot_time.tv_sec);
-        *p = htonl((u32)clp->cl_boot_time.tv_nsec);
-        args.verifier = &verifier;
+        nfs4_construct_boot_verifier(clp, &verifier);
 
         args.id_len = scnprintf(args.id, sizeof(args.id),
                                 "%s/%s.%s/%u",