Re: OOPS, ip -f inet6 route get fec0::1, linux-2.6.26, ip6_route_output, rt6_fill_node+0x175

David Miller wrote:

From: Eugene Teo <redacted>
Date: Mon, 11 Aug 2008 16:40:24 +0800

quoted

Brian Haley wrote:

quoted

Alexey Dobriyan wrote:

quoted

On Thu, Aug 07, 2008 at 07:00:56PM +0200, John Gumb wrote:

quoted

Scenario: no ipv6 default route set.
# ip -f inet6 route get fec0::1

BUG: unable to handle kernel NULL pointer dereference at 00000000
IP: [<c0369b85>] rt6_fill_node+0x175/0x3b0
EIP is at rt6_fill_node+0x175/0x3b0

0xffffffff80424dd3 is in rt6_fill_node (net/ipv6/route.c:2191).
2186                    } else
2187    #endif
2188                            NLA_PUT_U32(skb, RTA_IIF, iif);
2189            } else if (dst) {
2190                    struct in6_addr saddr_buf;
2191      ====>         if
(ipv6_dev_get_saddr(ip6_dst_idev(&rt->u.dst)->dev,
                           ^^^^^^^^^^^^^^^^^^^^^^^^
                                   NULL

2192                                           dst, 0, &saddr_buf) == 0)
2193                            NLA_PUT(skb, RTA_PREFSRC, 16,
&saddr_buf);
2194            }

The commit that changed this can't be reverted easily, but the patch
below works for me.

Fix NULL de-reference in rt6_fill_node() when there's no IPv6 input
device present in the dst entry.

Signed-off-by: Brian Haley <redacted>

Cc: Stable <stable@kernel.org>

We've already determined from one tester that the behavior is
changing with Brian's patch.  Furthermore I haven't applied it
to mainline so it isn't anywhere near being submittable for
-stable.

With the patch I posted, this is the behaviour I get:

$ ip -f inet6 route get fec0::1
unreachable fec0::1 dev lo  table unspec  proto none  src
fe80::214:4fff:fe0f:7332  metric -1  error -101 hoplimit 255

John emailed me that he will be testing this patch. I have not tested
Brian's patch.

I submit all relevant networking bug fixes to -stable when they are
ready and in a proper state to be submitted, you don't have to do it
for me.  Sending me a gentle reminder or nudge, on the other hand, is
fine.

Thanks for letting me know. I wasn't familiar, but I welcome the hint.

Thanks,
Eugene