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flow_dissector: Fix unaligned access in __skb_flow_dissector when used by eth_get_headlen

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This patch fixes an issue with unaligned accesses when using
eth_get_headlen on a page that was DMA aligned instead of being IP aligned.
The fact is when trying to check the length we don't need to be looking at
the flow label so we can reorder the checks to first check if we are
supposed to gather the flow label and then make the call to actually get
it.

v2:  Updated path so that either STOP_AT_FLOW_LABEL or KEY_FLOW_LABEL can
     cause us to check for the flow label.

Reported-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexander Duyck 2016-02-09 02:49:54 -08:00 committed by David S. Miller
parent f5a952c08e
commit 461547f315
1 changed files with 6 additions and 3 deletions
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9
net/core/flow_dissector.c
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@ -208,7 +208,6 @@ ip:
case htons(ETH_P_IPV6): { case htons(ETH_P_IPV6): {
const struct ipv6hdr *iph; const struct ipv6hdr *iph;
struct ipv6hdr _iph; struct ipv6hdr _iph;
__be32 flow_label;
ipv6: ipv6:
iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph); iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph);
@ -230,8 +229,12 @@ ipv6:
key_control->addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS; key_control->addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS;
} }
flow_label = ip6_flowlabel(iph); if ((dissector_uses_key(flow_dissector,
if (flow_label) { FLOW_DISSECTOR_KEY_FLOW_LABEL) ||
(flags & FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL)) &&
ip6_flowlabel(iph)) {
__be32 flow_label = ip6_flowlabel(iph);
if (dissector_uses_key(flow_dissector, if (dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_FLOW_LABEL)) { FLOW_DISSECTOR_KEY_FLOW_LABEL)) {
key_tags = skb_flow_dissector_target(flow_dissector, key_tags = skb_flow_dissector_target(flow_dissector,