NFSD: 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.

We can fix most of this by using a __be32 array to generate the
verifier's contents and then byte-copying it into the verifier field.

However, there is one spot where there is a backwards compatibility
constraint: the do_nfsd_create() call expects a verifier which is
32-bit aligned.  Fix this spot by forcing the alignment of the create
verifier in the nfsd4_open args structure.

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: J. Bruce Fields <bfields@redhat.com>

1 files changed, 11 insertions, 8 deletions

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 3f7dbc410e3..2a9036670b8 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -489,14 +489,20 @@ nfsd4_access(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 			   &access->ac_supported);
 }
 
+static void gen_boot_verifier(nfs4_verifier *verifier)
+{
+	__be32 verf[2];
+
+	verf[0] = (__be32)nfssvc_boot.tv_sec;
+	verf[1] = (__be32)nfssvc_boot.tv_usec;
+	memcpy(verifier->data, verf, sizeof(verifier->data));
+}
+
 static __be32
 nfsd4_commit(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	     struct nfsd4_commit *commit)
 {
-	u32 *p = (u32 *)commit->co_verf.data;
-	*p++ = nfssvc_boot.tv_sec;
-	*p++ = nfssvc_boot.tv_usec;
-
+	gen_boot_verifier(&commit->co_verf);
 	return nfsd_commit(rqstp, &cstate->current_fh, commit->co_offset,
 			     commit->co_count);
 }
@@ -873,7 +879,6 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 {
 	stateid_t *stateid = &write->wr_stateid;
 	struct file *filp = NULL;
-	u32 *p;
 	__be32 status = nfs_ok;
 	unsigned long cnt;
 
@@ -895,9 +900,7 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 
 	cnt = write->wr_buflen;
 	write->wr_how_written = write->wr_stable_how;
-	p = (u32 *)write->wr_verifier.data;
-	*p++ = nfssvc_boot.tv_sec;
-	*p++ = nfssvc_boot.tv_usec;
+	gen_boot_verifier(&write->wr_verifier);
 
 	status =  nfsd_write(rqstp, &cstate->current_fh, filp,
 			     write->wr_offset, rqstp->rq_vec, write->wr_vlen,