| From | Ben Hutchings <> | Date | Wed, 27 Apr 2016 01:02:21 +0200 | Subject | [PATCH 3.16 204/217] macvtap: always pass ethernet header in linear |
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3.16.35-rc1 review patch. If anyone has any objections, please let me know.
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From: Willem de Bruijn <willemb@google.com>
[ Upstream commit 8e2ad4113ce4671686740f808ff2795395c39eef ]
The stack expects link layer headers in the skb linear section. Macvtap can create skbs with llheader in frags in edge cases: when (IFF_VNET_HDR is off or vnet_hdr.hdr_len < ETH_HLEN) and prepad + len > PAGE_SIZE and vnet_hdr.flags has no or bad csum.
Add checks to ensure linear is always at least ETH_HLEN. At this point, len is already ensured to be >= ETH_HLEN.
For backwards compatiblity, rounds up short vnet_hdr.hdr_len. This differs from tap and packet, which return an error.
Fixes b9fb9ee07e67 ("macvtap: add GSO/csum offload support") Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.16: don't use macvtap16_to_cpu()] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- drivers/net/macvtap.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
--- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -690,6 +690,8 @@ static ssize_t macvtap_get_user(struct m copylen = vnet_hdr.hdr_len ? vnet_hdr.hdr_len : GOODCOPY_LEN; if (copylen > good_linear) copylen = good_linear; + else if (copylen < ETH_HLEN) + copylen = ETH_HLEN; linear = copylen; if (iov_pages(iv, vnet_hdr_len + copylen, count) <= MAX_SKB_FRAGS) @@ -698,10 +700,11 @@ static ssize_t macvtap_get_user(struct m if (!zerocopy) { copylen = len; - if (vnet_hdr.hdr_len > good_linear) + linear = vnet_hdr.hdr_len; + if (linear > good_linear) linear = good_linear; - else - linear = vnet_hdr.hdr_len; + else if (linear < ETH_HLEN) + linear = ETH_HLEN; } skb = macvtap_alloc_skb(&q->sk, MACVTAP_RESERVE, copylen,
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