NFSv3: Fix posix ACL code

Fix a memory leak due to allocation in the XDR layer. In cases where the
RPC call needs to be retransmitted, we end up allocating new pages without
clearing the old ones. Fix this by moving the allocation into
nfs3_proc_setacls().

Also fix an issue discovered by Kevin Rudd, whereby the amount of memory
reserved for the acls in the xdr_buf->head was miscalculated, and causing
corruption.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

4 files changed, 39 insertions, 27 deletions

diff --git a/fs/nfs/nfs3acl.c b/fs/nfs/nfs3acl.c
index cef6255..6bbf0e6 100644
--- a/fs/nfs/nfs3acl.c
+++ b/fs/nfs/nfs3acl.c
@@ -292,7 +292,7 @@ static int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 {
 	struct nfs_server *server = NFS_SERVER(inode);
 	struct nfs_fattr fattr;
-	struct page *pages[NFSACL_MAXPAGES] = { };
+	struct page *pages[NFSACL_MAXPAGES];
 	struct nfs3_setaclargs args = {
 		.inode = inode,
 		.mask = NFS_ACL,
@@ -303,7 +303,7 @@ static int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 		.rpc_argp	= &args,
 		.rpc_resp	= &fattr,
 	};
-	int status, count;
+	int status;
 
 	status = -EOPNOTSUPP;
 	if (!nfs_server_capable(inode, NFS_CAP_ACLS))
@@ -319,6 +319,20 @@ static int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 	if (S_ISDIR(inode->i_mode)) {
 		args.mask |= NFS_DFACL;
 		args.acl_default = dfacl;
+		args.len = nfsacl_size(acl, dfacl);
+	} else
+		args.len = nfsacl_size(acl, NULL);
+
+	if (args.len > NFS_ACL_INLINE_BUFSIZE) {
+		unsigned int npages = 1 + ((args.len - 1) >> PAGE_SHIFT);
+
+		status = -ENOMEM;
+		do {
+			args.pages[args.npages] = alloc_page(GFP_KERNEL);
+			if (args.pages[args.npages] == NULL)
+				goto out_freepages;
+			args.npages++;
+		} while (args.npages < npages);
 	}
 
 	dprintk("NFS call setacl\n");
@@ -329,10 +343,6 @@ static int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 	nfs_zap_acl_cache(inode);
 	dprintk("NFS reply setacl: %d\n", status);
 
-	/* pages may have been allocated at the xdr layer. */
-	for (count = 0; count < NFSACL_MAXPAGES && args.pages[count]; count++)
-		__free_page(args.pages[count]);
-
 	switch (status) {
 		case 0:
 			status = nfs_refresh_inode(inode, &fattr);
@@ -346,6 +356,11 @@ static int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 		case -ENOTSUPP:
 			status = -EOPNOTSUPP;
 	}
+out_freepages:
+	while (args.npages != 0) {
+		args.npages--;
+		__free_page(args.pages[args.npages]);
+	}
 out:
 	return status;
 }
diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
index 11cddde..6cdeacf 100644
--- a/fs/nfs/nfs3xdr.c
+++ b/fs/nfs/nfs3xdr.c
@@ -82,8 +82,10 @@
 #define NFS3_commitres_sz	(1+NFS3_wcc_data_sz+2)
 
 #define ACL3_getaclargs_sz	(NFS3_fh_sz+1)
-#define ACL3_setaclargs_sz	(NFS3_fh_sz+1+2*(2+5*3))
-#define ACL3_getaclres_sz	(1+NFS3_post_op_attr_sz+1+2*(2+5*3))
+#define ACL3_setaclargs_sz	(NFS3_fh_sz+1+ \
+				XDR_QUADLEN(NFS_ACL_INLINE_BUFSIZE))
+#define ACL3_getaclres_sz	(1+NFS3_post_op_attr_sz+1+ \
+				XDR_QUADLEN(NFS_ACL_INLINE_BUFSIZE))
 #define ACL3_setaclres_sz	(1+NFS3_post_op_attr_sz)
 
 /*
@@ -703,28 +705,18 @@ nfs3_xdr_setaclargs(struct rpc_rqst *req, __be32 *p,
                    struct nfs3_setaclargs *args)
 {
 	struct xdr_buf *buf = &req->rq_snd_buf;
-	unsigned int base, len_in_head, len = nfsacl_size(
-		(args->mask & NFS_ACL)   ? args->acl_access  : NULL,
-		(args->mask & NFS_DFACL) ? args->acl_default : NULL);
-	int count, err;
+	unsigned int base;
+	int err;
 
 	p = xdr_encode_fhandle(p, NFS_FH(args->inode));
 	*p++ = htonl(args->mask);
-	base = (char *)p - (char *)buf->head->iov_base;
-	/* put as much of the acls into head as possible. */
-	len_in_head = min_t(unsigned int, buf->head->iov_len - base, len);
-	len -= len_in_head;
-	req->rq_slen = xdr_adjust_iovec(req->rq_svec, p + (len_in_head >> 2));
-
-	for (count = 0; (count << PAGE_SHIFT) < len; count++) {
-		args->pages[count] = alloc_page(GFP_KERNEL);
-		if (!args->pages[count]) {
-			while (count)
-				__free_page(args->pages[--count]);
-			return -ENOMEM;
-		}
-	}
-	xdr_encode_pages(buf, args->pages, 0, len);
+	req->rq_slen = xdr_adjust_iovec(req->rq_svec, p);
+	base = req->rq_slen;
+
+	if (args->npages != 0)
+		xdr_encode_pages(buf, args->pages, 0, args->len);
+	else
+		req->rq_slen += args->len;
 
 	err = nfsacl_encode(buf, base, args->inode,
 			    (args->mask & NFS_ACL) ?
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index a550b52..2e5f000 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -406,6 +406,8 @@ struct nfs3_setaclargs {
 	int			mask;
 	struct posix_acl *	acl_access;
 	struct posix_acl *	acl_default;
+	size_t			len;
+	unsigned int		npages;
 	struct page **		pages;
 };
 
diff --git a/include/linux/nfsacl.h b/include/linux/nfsacl.h
index 54487a9..43011b6 100644
--- a/include/linux/nfsacl.h
+++ b/include/linux/nfsacl.h
@@ -37,6 +37,9 @@
 #define NFSACL_MAXPAGES		((2*(8+12*NFS_ACL_MAX_ENTRIES) + PAGE_SIZE-1) \
 				 >> PAGE_SHIFT)
 
+#define NFS_ACL_MAX_ENTRIES_INLINE	(5)
+#define NFS_ACL_INLINE_BUFSIZE	((2*(2+3*NFS_ACL_MAX_ENTRIES_INLINE)) << 2)
+
 static inline unsigned int
 nfsacl_size(struct posix_acl *acl_access, struct posix_acl *acl_default)
 {