MFC: r283273

The NFS client wasn't handling getdirentries(2) requests for sizes
that are not an exact multiple of DIRBLKSIZ correctly. Fortunately
readdir(3) always uses an exact multiple of DIRBLKSIZ, so few applications
were affected. This patch fixes this problem by reducing the size
of the directory read to an exact multiple of DIRBLKSIZ.

1 files changed, 15 insertions, 1 deletions

diff --git a/sys/fs/nfsclient/nfs_clvnops.c b/sys/fs/nfsclient/nfs_clvnops.c
index 731d6a2..1013164 100644
--- a/sys/fs/nfsclient/nfs_clvnops.c
+++ b/sys/fs/nfsclient/nfs_clvnops.c
@@ -2211,7 +2211,7 @@ nfs_readdir(struct vop_readdir_args *ap)
 	struct vnode *vp = ap->a_vp;
 	struct nfsnode *np = VTONFS(vp);
 	struct uio *uio = ap->a_uio;
-	ssize_t tresid;
+	ssize_t tresid, left;
 	int error = 0;
 	struct vattr vattr;
 	
@@ -2240,6 +2240,17 @@ nfs_readdir(struct vop_readdir_args *ap)
 	}
 
 	/*
+	 * NFS always guarantees that directory entries don't straddle
+	 * DIRBLKSIZ boundaries.  As such, we need to limit the size
+	 * to an exact multiple of DIRBLKSIZ, to avoid copying a partial
+	 * directory entry.
+	 */
+	left = uio->uio_resid % DIRBLKSIZ;
+	if (left == uio->uio_resid)
+		return (EINVAL);
+	uio->uio_resid -= left;
+
+	/*
 	 * Call ncl_bioread() to do the real work.
 	 */
 	tresid = uio->uio_resid;
@@ -2250,6 +2261,9 @@ nfs_readdir(struct vop_readdir_args *ap)
 		if (ap->a_eofflag != NULL)
 			*ap->a_eofflag = 1;
 	}
+	
+	/* Add the partial DIRBLKSIZ (left) back in. */
+	uio->uio_resid += left;
 	return (error);
 }