[PATCH] nfs client, kernel 2.4.31: readlink result overflow

[Assar <assar@permabit.com>]

In 2.4.31, the v2/3 nfs readlink accepts too long symlinks.
I have tested this by having a server return long symlinks.
2.6.13 does not to my reading have this problem.

diff -u linux-2.4.31.orig/fs/nfs/nfs2xdr.c linux-2.4.31/fs/nfs/nfs2xdr.c
--- linux-2.4.31.orig/fs/nfs/nfs2xdr.c	2002-11-28 18:53:15.000000000 -0500
+++ linux-2.4.31/fs/nfs/nfs2xdr.c	2005-09-07 17:36:04.000000000 -0400
@@ -571,8 +571,8 @@
 	strlen = (u32*)kmap(rcvbuf->pages[0]);
 	/* Convert length of symlink */
 	len = ntohl(*strlen);
-	if (len > rcvbuf->page_len)
-		len = rcvbuf->page_len;
+	if (len > rcvbuf->page_len - 1 - 4)
+		len = rcvbuf->page_len - 1 - 4;
 	*strlen = len;
 	/* NULL terminate the string we got */
 	string = (char *)(strlen + 1);
diff -u linux-2.4.31.orig/fs/nfs/nfs3xdr.c linux-2.4.31/fs/nfs/nfs3xdr.c
--- linux-2.4.31.orig/fs/nfs/nfs3xdr.c	2003-11-28 13:26:21.000000000 -0500
+++ linux-2.4.31/fs/nfs/nfs3xdr.c	2005-09-07 17:53:10.000000000 -0400
@@ -759,8 +759,8 @@
 	strlen = (u32*)kmap(rcvbuf->pages[0]);
 	/* Convert length of symlink */
 	len = ntohl(*strlen);
-	if (len > rcvbuf->page_len)
-		len = rcvbuf->page_len;
+	if (len > rcvbuf->page_len - 1 - 4)
+		len = rcvbuf->page_len - 1 - 4;
 	*strlen = len;
 	/* NULL terminate the string we got */
 	string = (char *)(strlen + 1);
-
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