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Commit f5271fff authored by YOSHIFUJI Hideaki / 吉藤英明's avatar YOSHIFUJI Hideaki / 吉藤英明 Committed by Pablo Neira Ayuso
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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: default avatarYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 4b47bc9a

net/ipv6/netfilter/ip6t_NPT.c

+3 −3
Original line number Diff line number Diff line
@@ -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;