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Date: Mon, 18 Apr 2016 11:28:33 +0900 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Willem de Bruijn <willemb@...gle.com>, "David S. Miller" <davem@...emloft.net> Subject: [PATCH 4.4 051/137] macvtap: always pass ethernet header in linear 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Willem de Bruijn <willemb@...gle.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@...gle.com> Signed-off-by: David S. Miller <davem@...emloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- drivers/net/macvtap.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -760,6 +760,8 @@ static ssize_t macvtap_get_user(struct m macvtap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN; if (copylen > good_linear) copylen = good_linear; + else if (copylen < ETH_HLEN) + copylen = ETH_HLEN; linear = copylen; i = *from; iov_iter_advance(&i, copylen); @@ -769,10 +771,11 @@ static ssize_t macvtap_get_user(struct m if (!zerocopy) { copylen = len; - if (macvtap16_to_cpu(q, vnet_hdr.hdr_len) > good_linear) + linear = macvtap16_to_cpu(q, vnet_hdr.hdr_len); + if (linear > good_linear) linear = good_linear; - else - linear = macvtap16_to_cpu(q, 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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