From: Alice Mikityanska The cited commit started using msslen for uh->len, but still uses newlen to adjust uh->check. Although the checksum is ignored in most cases due to the hardware offload, __udp_gso_segment attempts to maintain the correct one. Fix uh->check and adjust it by the right value. Additionally, after the fix, newlen becomes assigned and unused before the loop. The code can be simplified a bit if mss adjustment is dropped, so that newlen becomes equal to msslen before the loop, and msslen can be also dropped, saving a few lines of code. This brings us back to one variable, drops an unneeded arithmetic for mss, and fixes the UDP checksum. Fixes: b10b446ce7ad ("udp: gso: Use single MSS length in UDP header for GSO_PARTIAL") Signed-off-by: Alice Mikityanska Reviewed-by: Willem de Bruijn Signed-off-by: Gal Pressman --- net/ipv4/udp_offload.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-) diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index a0813d425b71..2578aa7f9ff9 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -482,11 +482,11 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb, struct sock *sk = gso_skb->sk; unsigned int sum_truesize = 0; struct sk_buff *segs, *seg; - __be16 newlen, msslen; struct udphdr *uh; unsigned int mss; bool copy_dtor; __sum16 check; + __be16 newlen; int ret = 0; mss = skb_shinfo(gso_skb)->gso_size; @@ -555,15 +555,6 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb, return segs; } - msslen = htons(sizeof(*uh) + mss); - - /* GSO partial and frag_list segmentation only requires splitting - * the frame into an MSS multiple and possibly a remainder, both - * cases return a GSO skb. So update the mss now. - */ - if (skb_is_gso(segs)) - mss *= skb_shinfo(segs)->gso_segs; - seg = segs; uh = udp_hdr(seg); @@ -586,7 +577,7 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb, if (!seg->next) break; - uh->len = msslen; + uh->len = newlen; uh->check = check; if (seg->ip_summed == CHECKSUM_PARTIAL) -- 2.52.0