1 files changed, 41 insertions, 13 deletions

diff --git a/fs/nfs_common/nfsacl.c b/fs/nfs_common/nfsacl.c
index fc1c52571c03..84c27d69d421 100644
--- a/fs/nfs_common/nfsacl.c
+++ b/fs/nfs_common/nfsacl.c
@@ -42,6 +42,11 @@ struct nfsacl_encode_desc {
         gid_t gid;
 };
 
+struct nfsacl_simple_acl {
+        struct posix_acl acl;
+        struct posix_acl_entry ace[4];
+};
+
 static int
 xdr_nfsace_encode(struct xdr_array2_desc *desc, void *elem)
 {
@@ -72,9 +77,20 @@ xdr_nfsace_encode(struct xdr_array2_desc *desc, void *elem)
         return 0;
 }
 
-unsigned int
-nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode,
-              struct posix_acl *acl, int encode_entries, int typeflag)
+/**
+ * nfsacl_encode - Encode an NFSv3 ACL
+ *
+ * @buf: destination xdr_buf to contain XDR encoded ACL
+ * @base: byte offset in xdr_buf where XDR'd ACL begins
+ * @inode: inode of file whose ACL this is
+ * @acl: posix_acl to encode
+ * @encode_entries: whether to encode ACEs as well
+ * @typeflag: ACL type: NFS_ACL_DEFAULT or zero
+ *
+ * Returns size of encoded ACL in bytes or a negative errno value.
+ */
+int nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode,
+                  struct posix_acl *acl, int encode_entries, int typeflag)
 {
         int entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0;
         struct nfsacl_encode_desc nfsacl_desc = {
@@ -88,17 +104,22 @@ nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode,
                 .uid = inode->i_uid,
                 .gid = inode->i_gid,
         };
+        struct nfsacl_simple_acl aclbuf;
         int err;
-        struct posix_acl *acl2 = NULL;
 
         if (entries > NFS_ACL_MAX_ENTRIES ||
             xdr_encode_word(buf, base, entries))
                 return -EINVAL;
         if (encode_entries && acl && acl->a_count == 3) {
-                /* Fake up an ACL_MASK entry. */
-                acl2 = posix_acl_alloc(4, GFP_KERNEL);
-                if (!acl2)
-                        return -ENOMEM;
+                struct posix_acl *acl2 = &aclbuf.acl;
+
+                /* Avoid the use of posix_acl_alloc().  nfsacl_encode() is
+                 * invoked in contexts where a memory allocation failure is
+                 * fatal.  Fortunately this fake ACL is small enough to
+                 * construct on the stack. */
+                memset(acl2, 0, sizeof(acl2));
+                posix_acl_init(acl2, 4);
+
                 /* Insert entries in canonical order: other orders seem
                  to confuse Solaris VxFS. */
                 acl2->a_entries[0] = acl->a_entries[0];  /* ACL_USER_OBJ */
@@ -109,8 +130,6 @@ nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode,
                 nfsacl_desc.acl = acl2;
         }
         err = xdr_encode_array2(buf, base + 4, &nfsacl_desc.desc);
-        if (acl2)
-                posix_acl_release(acl2);
         if (!err)
                 err = 8 + nfsacl_desc.desc.elem_size *
                           nfsacl_desc.desc.array_len;
@@ -224,9 +243,18 @@ posix_acl_from_nfsacl(struct posix_acl *acl)
         return 0;
 }
 
-unsigned int
-nfsacl_decode(struct xdr_buf *buf, unsigned int base, unsigned int *aclcnt,
-              struct posix_acl **pacl)
+/**
+ * nfsacl_decode - Decode an NFSv3 ACL
+ *
+ * @buf: xdr_buf containing XDR'd ACL data to decode
+ * @base: byte offset in xdr_buf where XDR'd ACL begins
+ * @aclcnt: count of ACEs in decoded posix_acl
+ * @pacl: buffer in which to place decoded posix_acl
+ *
+ * Returns the length of the decoded ACL in bytes, or a negative errno value.
+ */
+int nfsacl_decode(struct xdr_buf *buf, unsigned int base, unsigned int *aclcnt,
+                  struct posix_acl **pacl)
 {
         struct nfsacl_decode_desc nfsacl_desc = {
                 .desc = {