linux-kernel - [PATCH v2 net 2/2] macvtap: correctly linearize skb when zerocopy is used

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1373435008-19407-2-git-send-email-jasowang@redhat.com>
Date:	Wed, 10 Jul 2013 13:43:28 +0800
From:	Jason Wang <jasowang@...hat.com>
To:	davem@...emloft.net, mst@...hat.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc:	Jason Wang <jasowang@...hat.com>
Subject: [PATCH v2 net 2/2] macvtap: correctly linearize skb when zerocopy is used

Userspace may produce vectors greater than MAX_SKB_FRAGS. When we try to
linearize parts of the skb to let the rest of iov to be fit in
the frags, we need count copylen into linear when calling macvtap_alloc_skb()
instead of partly counting it into data_len. Since this breaks
zerocopy_sg_from_iovec() since its inner counter assumes nr_frags should
be zero at beginning. This cause nr_frags to be increased wrongly without
setting the correct frags.

This bug were introduced from b92946e2919134ebe2a4083e4302236295ea2a73
(macvtap: zerocopy: validate vectors before building skb).

Cc: Michael S. Tsirkin <mst@...hat.com>
Signed-off-by: Jason Wang <jasowang@...hat.com>
---
- This patch is needed for stable.
- Changes from v1: introduce a local variable to track linear size.
---
 drivers/net/macvtap.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index b6dd6a7..502d948 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -647,6 +647,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
 	int vnet_hdr_len = 0;
 	int copylen = 0;
 	bool zerocopy = false;
+	size_t linear;
 
 	if (q->flags & IFF_VNET_HDR) {
 		vnet_hdr_len = q->vnet_hdr_sz;
@@ -701,11 +702,14 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
 			copylen = vnet_hdr.hdr_len;
 		if (!copylen)
 			copylen = GOODCOPY_LEN;
-	} else
+		linear = copylen;
+	} else {
 		copylen = len;
+		linear = vnet_hdr.hdr_len;
+	}
 
 	skb = macvtap_alloc_skb(&q->sk, NET_IP_ALIGN, copylen,
-				vnet_hdr.hdr_len, noblock, &err);
+				linear, noblock, &err);
 	if (!skb)
 		goto err;
 
-- 
1.7.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/