svn commit: r283273 - head/sys/fs/nfsclient

[Rick Macklem]

Author: rmacklem
Date: Thu May 21 23:14:18 2015
New Revision: 283273
URL: https://svnweb.freebsd.org/changeset/base/283273

Log:
  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.
  
  Tested by:	trasz
  Reported by:	trasz
  Reviewed by:	trasz
  MFC after:	2 weeks

Modified:
  head/sys/fs/nfsclient/nfs_clvnops.c

Modified: head/sys/fs/nfsclient/nfs_clvnops.c
==============================================================================
--- head/sys/fs/nfsclient/nfs_clvnops.c	Thu May 21 22:50:39 2015	(r283272)
+++ head/sys/fs/nfsclient/nfs_clvnops.c	Thu May 21 23:14:18 2015	(r283273)
@@ -2210,7 +2210,7 @@ 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;
 	
@@ -2239,6 +2239,17 @@ 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;
@@ -2249,6 +2260,9 @@ 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);
 }