This is a note to let you know that I've just added the patch titled
macvtap: correctly linearize skb when zerocopy is used
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
macvtap-correctly-linearize-skb-when-zerocopy-is-used.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2c2017d0d3e8b8b7f3056aa204196a9bf27b1268 Mon Sep 17 00:00:00 2001
From: Jason Wang <jasowang@xxxxxxxxxx>
Date: Wed, 10 Jul 2013 13:43:28 +0800
Subject: macvtap: correctly linearize skb when zerocopy is used
From: Jason Wang <jasowang@xxxxxxxxxx>
[ Upstream commit 61d46bf979d5cd7c164709a80ad5676a35494aae ]
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@xxxxxxxxxx>
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/macvtap.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -656,6 +656,7 @@ static ssize_t macvtap_get_user(struct 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;
@@ -710,11 +711,14 @@ static ssize_t macvtap_get_user(struct 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;
Patches currently in stable-queue which might be from jasowang@xxxxxxxxxx are
queue-3.4/macvtap-correctly-linearize-skb-when-zerocopy-is-used.patch
queue-3.4/macvtap-fix-recovery-from-gup-errors.patch
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