From 52cbd23a119c6ebf40a527e53f3402d2ea38eccb Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Wed, 3 Feb 2021 14:29:52 -0500 Subject: udp: fix skb_copy_and_csum_datagram with odd segment sizes When iteratively computing a checksum with csum_block_add, track the offset "pos" to correctly rotate in csum_block_add when offset is odd. The open coded implementation of skb_copy_and_csum_datagram did this. With the switch to __skb_datagram_iter calling csum_and_copy_to_iter, pos was reinitialized to 0 on each call. Bring back the pos by passing it along with the csum to the callback. Changes v1->v2 - pass csum value, instead of csump pointer (Alexander Duyck) Link: https://lore.kernel.org/netdev/20210128152353.GB27281@optiplex/ Fixes: 950fcaecd5cc ("datagram: consolidate datagram copy to iter helpers") Reported-by: Oliver Graute Signed-off-by: Willem de Bruijn Reviewed-by: Alexander Duyck Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20210203192952.1849843-1-willemdebruijn.kernel@gmail.com Signed-off-by: Jakub Kicinski --- net/core/datagram.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'net/core/datagram.c') diff --git a/net/core/datagram.c b/net/core/datagram.c index 81809fa735a7..15ab9ffb27fe 100644 --- a/net/core/datagram.c +++ b/net/core/datagram.c @@ -721,8 +721,16 @@ static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset, struct iov_iter *to, int len, __wsum *csump) { - return __skb_datagram_iter(skb, offset, to, len, true, - csum_and_copy_to_iter, csump); + struct csum_state csdata = { .csum = *csump }; + int ret; + + ret = __skb_datagram_iter(skb, offset, to, len, true, + csum_and_copy_to_iter, &csdata); + if (ret) + return ret; + + *csump = csdata.csum; + return 0; } /** -- cgit v1.2.3-59-g8ed1b