Messages in this thread Patches in this message | | | Date | Wed, 9 Jul 2003 19:52:37 +0200 | From | Jean-Luc Richier <> | Subject | Bug in Linux 2.5.74 IPv6 routing |
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There is a bug in IPv6 route calculation since kernel 2.5.71. It affects all routes with prefix length != 0 (mod 8) The bug is as follows: do: ip -6 route add 2000::/3 via 2001:688:121:10::1 ip -6 route It shows a route for ::/3, not for 2000::/3
The bug was introduced when changing function ipv6_addr_prefix to inline status (and moving it from net/ipv6/route.c to include/net/ipv6.h).
At the same time the = and the memset in the function have been swapped. (cf patch 1 below). With the new code, with a prefix length = 3, the function first sets the correct value in pfx->s6_addr[0] and AFTER does a memset(pfx->s6_addr + 0, 0, 16 - 0) which overwrites pfx->s6_addr[0]. The previous was doing the memset first.
There are 2 solutions to correct this bug: - The first solution is to restore the order between = and memset (see patch 1). But I suppose that there is a reason for this swap. In fact the old code does not work if the 2 addr arguments are equal, the new code (corrected) works. - So I suggest an other solution (see patch 2): if the prefix length is not 0 mod 8, increase o, as pfx->s6_addr[o) is already set.
PATCH 1: (reverse to previous code) --- linux-2.5.74/include/net/ipv6.h.DIST 2003-07-02 22:53:44.000000000 +0200 +++ linux-2.5.74/include/net/ipv6.h 2003-07-09 19:03:13.195128011 +0200 @@ -276,10 +276,10 @@ b = plen & 0x7; memcpy(pfx->s6_addr, addr, o); - if (b != 0) - pfx->s6_addr[o] = addr->s6_addr[o] & (0xff00 >> b); if (o < 16) memset(pfx->s6_addr + o, 0, 16 - o); + if (b != 0) + pfx->s6_addr[o] = addr->s6_addr[o] & (0xff00 >> b); } #ifndef __HAVE_ARCH_ADDR_SET PATCH 2: avoid overwriting the set value --- linux-2.5.74/include/net/ipv6.h.DIST 2003-07-02 22:53:44.000000000 +0200 +++ linux-2.5.74/include/net/ipv6.h 2003-07-09 18:51:25.000000000 +0200 @@ -276,8 +276,10 @@ b = plen & 0x7; memcpy(pfx->s6_addr, addr, o); - if (b != 0) + if (b != 0) { pfx->s6_addr[o] = addr->s6_addr[o] & (0xff00 >> b); + o++; + } if (o < 16) memset(pfx->s6_addr + o, 0, 16 - o); }
-- Jean-Luc RICHIER (Jean-Luc.Richier@Imag.Fr richier@imag.fr) Laboratoire Logiciels, Systemes et Reseaux (LSR-IMAG) IMAG-CAMPUS, BP 72, F-38402 St Martin d'Heres Cedex Tel : +33 4 76 82 72 32 Fax : +33 4 76 82 72 87 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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