[ 25/73] netfilter: ip6t_NPT: Fix translation for non-multiple of 32 prefix lengths

From: Greg Kroah-Hartman
Date: Thu May 09 2013 - 18:56:59 EST


3.8-stable review patch. If anyone has any objections, please let me know.

------------------

From: Matthias Schiffer <mschiffer@xxxxxxxxxxxxxxxxxxxx>

commit 906b1c394d0906a154fbdc904ca506bceb515756 upstream.

The bitmask used for the prefix mangling was being calculated
incorrectly, leading to the wrong part of the address being replaced
when the prefix length wasn't a multiple of 32.

Signed-off-by: Matthias Schiffer <mschiffer@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
net/ipv6/netfilter/ip6t_NPT.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv6/netfilter/ip6t_NPT.c
+++ b/net/ipv6/netfilter/ip6t_NPT.c
@@ -57,7 +57,7 @@ static bool ip6t_npt_map_pfx(const struc
if (pfx_len - i >= 32)
mask = 0;
else
- mask = htonl(~((1 << (pfx_len - i)) - 1));
+ mask = htonl((1 << (i - pfx_len + 32)) - 1);

idx = i / 32;
addr->s6_addr32[idx] &= mask;


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