1 files changed, 6 insertions, 2 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index b44cf81d8178..509912a5ff98 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2388,8 +2388,12 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
          */
         TCP_SKB_CB(skb)->when = tcp_time_stamp;
 
-        /* make sure skb->data is aligned on arches that require it */
-        if (unlikely(NET_IP_ALIGN && ((unsigned long)skb->data & 3))) {
+        /* make sure skb->data is aligned on arches that require it
+         * and check if ack-trimming & collapsing extended the headroom
+         * beyond what csum_start can cover.
+         */
+        if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) ||
+                     skb_headroom(skb) >= 0xFFFF)) {
                 struct sk_buff *nskb = __pskb_copy(skb, MAX_TCP_HEADER,
                                                    GFP_ATOMIC);
                 return nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) :