From: Chuck Lever <chuck.lever@oracle.com>
Date: Thu, 30 Jun 2022 20:48:18 +0000 (-0400)
Subject: SUNRPC: Fix READ_PLUS crasher
X-Git-Tag: v5.4.204~51
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=76a477d3983640a233c7b51b601fb29b33d14295;p=thirdparty%2Fkernel%2Fstable.git

SUNRPC: Fix READ_PLUS crasher

commit a23dd544debcda4ee4a549ec7de59e85c3c8345c upstream.

Looks like there are still cases when "space_left - frag1bytes" can
legitimately exceed PAGE_SIZE. Ensure that xdr->end always remains
within the current encode buffer.

Reported-by: Bruce Fields <bfields@fieldses.org>
Reported-by: Zorro Lang <zlang@redhat.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216151
Fixes: 6c254bf3b637 ("SUNRPC: Fix the calculation of xdr->end in xdr_get_next_encode_buffer()")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index cb8740d156336..daa4165f11794 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -608,7 +608,7 @@ static __be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr,
 	 */
 	xdr->p = (void *)p + frag2bytes;
 	space_left = xdr->buf->buflen - xdr->buf->len;
-	if (space_left - nbytes >= PAGE_SIZE)
+	if (space_left - frag1bytes >= PAGE_SIZE)
 		xdr->end = (void *)p + PAGE_SIZE;
 	else
 		xdr->end = (void *)p + space_left - frag1bytes;