From f5271fff56c76e92fde122bcc02f102e99da5c8a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?YOSHIFUJI=20Hideaki=20/=20=E5=90=89=E8=97=A4=E8=8B=B1?= =?UTF-8?q?=E6=98=8E?= Date: Sat, 26 Jan 2013 08:37:48 +0000 Subject: [PATCH] netfilter: ip6t_NPT: Fix adjustment calculation Cast __wsum from/to __sum16 is wrong. Instead, apply appropriate conversion function: csum_unfold() or csum_fold(). [ The original patch has been modified to undo the final ~ that csum_fold returns. We only need to fold the 32-bit word that results from the checksum calculation into a 16-bit to ensure that the original subnet is restored appropriately. Spotted by Ulrich Weber. ] Signed-off-by: YOSHIFUJI Hideaki Signed-off-by: Pablo Neira Ayuso --- net/ipv6/netfilter/ip6t_NPT.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/net/ipv6/netfilter/ip6t_NPT.c b/net/ipv6/netfilter/ip6t_NPT.c index 7302b0b7b64..68788c84aee 100644 --- a/net/ipv6/netfilter/ip6t_NPT.c +++ b/net/ipv6/netfilter/ip6t_NPT.c @@ -30,7 +30,7 @@ static int ip6t_npt_checkentry(const struct xt_tgchk_param *par) (__force __wsum)npt->dst_pfx.in6.s6_addr16[i]); } - npt->adjustment = (__force __sum16) csum_sub(src_sum, dst_sum); + npt->adjustment = ~csum_fold(csum_sub(src_sum, dst_sum)); return 0; } @@ -66,8 +66,8 @@ static bool ip6t_npt_map_pfx(const struct ip6t_npt_tginfo *npt, return false; } - sum = (__force __sum16) csum_add((__force __wsum)addr->s6_addr16[idx], - npt->adjustment); + sum = ~csum_fold(csum_add(csum_unfold((__force __sum16)addr->s6_addr16[idx]), + csum_unfold(npt->adjustment))); if (sum == CSUM_MANGLED_0) sum = 0; *(__force __sum16 *)&addr->s6_addr16[idx] = sum;