diff options
| author | Dimitris Michailidis <dmichail@google.com> | 2018-10-19 17:07:13 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-10-20 01:13:42 -0700 |
| commit | d55bef5059dd057bd077155375c581b49d25be7e (patch) | |
| tree | 56269ac3365bde89b860aac7f5224e7054c6b226 /net | |
| parent | 48995423143a097527802e28d7add20e5a27677a (diff) | |
| download | linux-d55bef5059dd057bd077155375c581b49d25be7e.tar.gz | |
net: fix pskb_trim_rcsum_slow() with odd trim offset
We've been getting checksum errors involving small UDP packets, usually
59B packets with 1 extra non-zero padding byte. netdev_rx_csum_fault()
has been complaining that HW is providing bad checksums. Turns out the
problem is in pskb_trim_rcsum_slow(), introduced in commit 88078d98d1bb
("net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends").
The source of the problem is that when the bytes we are trimming start
at an odd address, as in the case of the 1 padding byte above,
skb_checksum() returns a byte-swapped value. We cannot just combine this
with skb->csum using csum_sub(). We need to use csum_block_sub() here
that takes into account the parity of the start address and handles the
swapping.
Matches existing code in __skb_postpull_rcsum() and esp_remove_trailer().
Fixes: 88078d98d1bb ("net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends")
Signed-off-by: Dimitris Michailidis <dmichail@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/skbuff.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 428094b577fc..f817f336595d 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1846,8 +1846,9 @@ int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len) if (skb->ip_summed == CHECKSUM_COMPLETE) { int delta = skb->len - len; - skb->csum = csum_sub(skb->csum, - skb_checksum(skb, len, delta, 0)); + skb->csum = csum_block_sub(skb->csum, + skb_checksum(skb, len, delta, 0), + len); } return __pskb_trim(skb, len); } |