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authorMartin KaFai Lau <kafai@fb.com>2015-11-11 20:51:06 +0100
committerDavid S. Miller <davem@davemloft.net>2015-11-15 23:12:37 +0100
commit0d3f6d297bfb7af24d0508460fdb3d1ec4903fa3 (patch)
tree90d07080b204355bfbc95f95105b1c364c477a1a
parentfjes: fix inconsistent indenting (diff)
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linux-0d3f6d297bfb7af24d0508460fdb3d1ec4903fa3.zip
ipv6: Avoid creating RTF_CACHE from a rt that is not managed by fib6 tree
The original bug report: https://bugzilla.redhat.com/show_bug.cgi?id=1272571 The setup has a IPv4 GRE tunnel running in a IPSec. The bug happens when ndisc starts sending router solicitation at the gre interface. The simplified oops stack is like: __lock_acquire+0x1b2/0x1c30 lock_acquire+0xb9/0x140 _raw_write_lock_bh+0x3f/0x50 __ip6_ins_rt+0x2e/0x60 ip6_ins_rt+0x49/0x50 ~~~~~~~~ __ip6_rt_update_pmtu.part.54+0x145/0x250 ip6_rt_update_pmtu+0x2e/0x40 ~~~~~~~~ ip_tunnel_xmit+0x1f1/0xf40 __gre_xmit+0x7a/0x90 ipgre_xmit+0x15a/0x220 dev_hard_start_xmit+0x2bd/0x480 __dev_queue_xmit+0x696/0x730 dev_queue_xmit+0x10/0x20 neigh_direct_output+0x11/0x20 ip6_finish_output2+0x21f/0x770 ip6_finish_output+0xa7/0x1d0 ip6_output+0x56/0x190 ~~~~~~~~ ndisc_send_skb+0x1d9/0x400 ndisc_send_rs+0x88/0xc0 ~~~~~~~~ The rt passed to ip6_rt_update_pmtu() is created by icmp6_dst_alloc() and it is not managed by the fib6 tree, so its rt6i_table == NULL. When __ip6_rt_update_pmtu() creates a RTF_CACHE clone, the newly created clone also has rt6i_table == NULL and it causes the ip6_ins_rt() oops. During pmtu update, we only want to create a RTF_CACHE clone from a rt which is currently managed (or owned) by the fib6 tree. It means either rt->rt6i_node != NULL or rt is a RTF_PCPU clone. It is worth to note that rt6i_table may not be NULL even it is not (yet) managed by the fib6 tree (e.g. addrconf_dst_alloc()). Hence, rt6i_node is a better check instead of rt6i_table. Fixes: 45e4fd26683c ("ipv6: Only create RTF_CACHE routes after encountering pmtu") Signed-off-by: Martin KaFai Lau <kafai@fb.com> Reported-by: Chris Siebenmann <cks-rhbugzilla@cs.toronto.edu> Cc: Chris Siebenmann <cks-rhbugzilla@cs.toronto.edu> Cc: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
-rw-r--r--net/ipv6/route.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index c8bc9b4ac328..74907c58a5c7 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1322,6 +1322,12 @@ static void rt6_do_update_pmtu(struct rt6_info *rt, u32 mtu)
rt6_update_expires(rt, net->ipv6.sysctl.ip6_rt_mtu_expires);
}
+static bool rt6_cache_allowed_for_pmtu(const struct rt6_info *rt)
+{
+ return !(rt->rt6i_flags & RTF_CACHE) &&
+ (rt->rt6i_flags & RTF_PCPU || rt->rt6i_node);
+}
+
static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
const struct ipv6hdr *iph, u32 mtu)
{
@@ -1335,7 +1341,7 @@ static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
if (mtu >= dst_mtu(dst))
return;
- if (rt6->rt6i_flags & RTF_CACHE) {
+ if (!rt6_cache_allowed_for_pmtu(rt6)) {
rt6_do_update_pmtu(rt6, mtu);
} else {
const struct in6_addr *daddr, *saddr;