Messages in this thread Patch in this message | | | Subject | Re: BUG: unable to handle kernel NULL pointer dereference in ipv6_select_ident | From | Eric Dumazet <> | Date | Thu, 22 Dec 2011 15:15:53 +0100 |
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Le jeudi 22 décembre 2011 à 10:04 +0000, Chris Boot a écrit :
> Eric, > > So far so good. I've had this running for several hours this morning > with more of the prodding that would normally have crashed it, both IPv4 > and IPv6, and it's holding up well. >
Thanks for testing.
Here is the official patch then (the .mtu() bit belongs to a separate patch)
[PATCH] net: introduce DST_NOPEER dst flag
Chris Boot reported crashes occurring in ipv6_select_ident().
[ 461.457562] RIP: 0010:[<ffffffff812dde61>] [<ffffffff812dde61>] ipv6_select_ident+0x31/0xa7
[ 461.578229] Call Trace: [ 461.580742] <IRQ> [ 461.582870] [<ffffffff812efa7f>] ? udp6_ufo_fragment+0x124/0x1a2 [ 461.589054] [<ffffffff812dbfe0>] ? ipv6_gso_segment+0xc0/0x155 [ 461.595140] [<ffffffff812700c6>] ? skb_gso_segment+0x208/0x28b [ 461.601198] [<ffffffffa03f236b>] ? ipv6_confirm+0x146/0x15e [nf_conntrack_ipv6] [ 461.608786] [<ffffffff81291c4d>] ? nf_iterate+0x41/0x77 [ 461.614227] [<ffffffff81271d64>] ? dev_hard_start_xmit+0x357/0x543 [ 461.620659] [<ffffffff81291cf6>] ? nf_hook_slow+0x73/0x111 [ 461.626440] [<ffffffffa0379745>] ? br_parse_ip_options+0x19a/0x19a [bridge] [ 461.633581] [<ffffffff812722ff>] ? dev_queue_xmit+0x3af/0x459 [ 461.639577] [<ffffffffa03747d2>] ? br_dev_queue_push_xmit+0x72/0x76 [bridge] [ 461.646887] [<ffffffffa03791e3>] ? br_nf_post_routing+0x17d/0x18f [bridge] [ 461.653997] [<ffffffff81291c4d>] ? nf_iterate+0x41/0x77 [ 461.659473] [<ffffffffa0374760>] ? br_flood+0xfa/0xfa [bridge] [ 461.665485] [<ffffffff81291cf6>] ? nf_hook_slow+0x73/0x111 [ 461.671234] [<ffffffffa0374760>] ? br_flood+0xfa/0xfa [bridge] [ 461.677299] [<ffffffffa0379215>] ? nf_bridge_update_protocol+0x20/0x20 [bridge] [ 461.684891] [<ffffffffa03bb0e5>] ? nf_ct_zone+0xa/0x17 [nf_conntrack] [ 461.691520] [<ffffffffa0374760>] ? br_flood+0xfa/0xfa [bridge] [ 461.697572] [<ffffffffa0374812>] ? NF_HOOK.constprop.8+0x3c/0x56 [bridge] [ 461.704616] [<ffffffffa0379031>] ? nf_bridge_push_encap_header+0x1c/0x26 [bridge] [ 461.712329] [<ffffffffa037929f>] ? br_nf_forward_finish+0x8a/0x95 [bridge] [ 461.719490] [<ffffffffa037900a>] ? nf_bridge_pull_encap_header+0x1c/0x27 [bridge] [ 461.727223] [<ffffffffa0379974>] ? br_nf_forward_ip+0x1c0/0x1d4 [bridge] [ 461.734292] [<ffffffff81291c4d>] ? nf_iterate+0x41/0x77 [ 461.739758] [<ffffffffa03748cc>] ? __br_deliver+0xa0/0xa0 [bridge] [ 461.746203] [<ffffffff81291cf6>] ? nf_hook_slow+0x73/0x111 [ 461.751950] [<ffffffffa03748cc>] ? __br_deliver+0xa0/0xa0 [bridge] [ 461.758378] [<ffffffffa037533a>] ? NF_HOOK.constprop.4+0x56/0x56 [bridge]
This is caused by bridge netfilter special dst_entry (fake_rtable), a special shared entry, where attaching an inetpeer makes no sense.
Problem is present since commit 87c48fa3b46 (ipv6: make fragment identifications less predictable)
Introduce DST_NOPEER dst flag and make sure ipv6_select_ident() and __ip_select_ident() fallback to the 'no peer attached' handling.
Reported-by: Chris Boot <bootc@bootc.net> Tested-by: Chris Boot <bootc@bootc.net> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> --- include/net/dst.h | 1 + net/bridge/br_netfilter.c | 2 +- net/ipv4/route.c | 4 ++-- net/ipv6/ip6_output.c | 2 +- 4 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/include/net/dst.h b/include/net/dst.h index 6faec1a..75766b4 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -53,6 +53,7 @@ struct dst_entry { #define DST_NOHASH 0x0008 #define DST_NOCACHE 0x0010 #define DST_NOCOUNT 0x0020 +#define DST_NOPEER 0x0040 short error; short obsolete; diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c index d6ec372..5693e5f 100644 --- a/net/bridge/br_netfilter.c +++ b/net/bridge/br_netfilter.c @@ -141,7 +141,7 @@ void br_netfilter_rtable_init(struct net_bridge *br) rt->dst.dev = br->dev; rt->dst.path = &rt->dst; dst_init_metrics(&rt->dst, br_dst_default_metrics, true); - rt->dst.flags = DST_NOXFRM; + rt->dst.flags = DST_NOXFRM | DST_NOPEER; rt->dst.ops = &fake_dst_ops; } diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 252c512..a5004f1 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1366,7 +1366,7 @@ void __ip_select_ident(struct iphdr *iph, struct dst_entry *dst, int more) { struct rtable *rt = (struct rtable *) dst; - if (rt) { + if (rt && !(rt->dst.flags & DST_NOPEER)) { if (rt->peer == NULL) rt_bind_peer(rt, rt->rt_dst, 1); @@ -1377,7 +1377,7 @@ void __ip_select_ident(struct iphdr *iph, struct dst_entry *dst, int more) iph->id = htons(inet_getid(rt->peer, more)); return; } - } else + } else if (!rt) printk(KERN_DEBUG "rt_bind_peer(0) @%p\n", __builtin_return_address(0)); diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 84d0bd5..ec56271 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -603,7 +603,7 @@ void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt) static atomic_t ipv6_fragmentation_id; int old, new; - if (rt) { + if (rt && !(rt->dst.flags & DST_NOPEER)) { struct inet_peer *peer; if (!rt->rt6i_peer)
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