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path: root/net/ipv4/udp_offload.c
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Diffstat (limited to 'net/ipv4/udp_offload.c')
-rw-r--r--net/ipv4/udp_offload.c15
1 files changed, 10 insertions, 5 deletions
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index f5abb1ae1358..8a3405a80260 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -40,13 +40,19 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
__be16 protocol = skb->protocol;
u16 mac_len = skb->mac_len;
int udp_offset, outer_hlen;
- u32 partial;
+ __wsum partial;
if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
goto out;
- /* adjust partial header checksum to negate old length */
- partial = (__force u32)uh->check + (__force u16)~uh->len;
+ /* Adjust partial header checksum to negate old length.
+ * We cannot rely on the value contained in uh->len as it is
+ * possible that the actual value exceeds the boundaries of the
+ * 16 bit length field due to the header being added outside of an
+ * IP or IPv6 frame that was already limited to 64K - 1.
+ */
+ partial = csum_sub(csum_unfold(uh->check),
+ (__force __wsum)htonl(skb->len));
/* setup inner skb. */
skb->encapsulation = 0;
@@ -119,8 +125,7 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
if (!need_csum)
continue;
- uh->check = ~csum_fold((__force __wsum)
- ((__force u32)len + partial));
+ uh->check = ~csum_fold(csum_add(partial, (__force __wsum)len));
if (skb->encapsulation || !offload_csum) {
uh->check = gso_make_checksum(skb, ~uh->check);