From: Björn Töpel <bjorn.topel@intel.com>
Date: Fri, 8 Mar 2019 07:57:27 +0000 (+0100)
Subject: xsk: fix to reject invalid options in Tx descriptor
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=c57b557b644da624982c36b74f608cdb7b902868;p=linux.git

xsk: fix to reject invalid options in Tx descriptor

Passing a non-existing option in the options member of struct
xdp_desc was, incorrectly, silently ignored. This patch addresses
that behavior, and drops any Tx descriptor with non-existing options.

We have examined existing user space code, and to our best knowledge,
no one is relying on the current incorrect behavior. AF_XDP is still
in its infancy, so from our perspective, the risk of breakage is very
low, and addressing this problem now is important.

Fixes: 35fcde7f8deb ("xsk: support for Tx")
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
---

diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index bcb5cbb40419f..610c0bdc0c2b8 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -174,8 +174,8 @@ static inline bool xskq_is_valid_desc(struct xsk_queue *q, struct xdp_desc *d)
 	if (!xskq_is_valid_addr(q, d->addr))
 		return false;
 
-	if (((d->addr + d->len) & q->chunk_mask) !=
-	    (d->addr & q->chunk_mask)) {
+	if (((d->addr + d->len) & q->chunk_mask) != (d->addr & q->chunk_mask) ||
+	    d->options) {
 		q->invalid_descs++;
 		return false;
 	}