NFS: Prevent memory allocation failure in nfsacl_encode()

nfsacl_encode() allocates memory in certain cases.  This of course
is not guaranteed to work.

Since commit 9f06c719 "SUNRPC: New xdr_streams XDR encoder API", the
kernel's XDR encoders can't return a result indicating possibly a
failure, so a memory allocation failure in nfsacl_encode() has become
fatal (ie, the XDR code Oopses) in some cases.

However, the allocated memory is a tiny fixed amount, on the order
of 40-50 bytes.  We can easily use a stack-allocated buffer for
this, with only a wee bit of nose-holding.

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

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/nfs/nfs3acl.c b/fs/nfs/nfs3acl.c
index 9f88c5f4c7e2..274342771655 100644
--- a/fs/nfs/nfs3acl.c
+++ b/fs/nfs/nfs3acl.c
@@ -311,8 +311,8 @@ static int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
         if (!nfs_server_capable(inode, NFS_CAP_ACLS))
                 goto out;
 
-        /* We are doing this here, because XDR marshalling can only
-           return -ENOMEM. */
+        /* We are doing this here because XDR marshalling does not
+         * return any results, it BUGs. */
         status = -ENOSPC;
         if (acl != NULL && acl->a_count > NFS_ACL_MAX_ENTRIES)
                 goto out;