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authorJonathan Lemon <jonathan.lemon@gmail.com>2019-04-14 14:21:29 -0700
committerDavid S. Miller <davem@davemloft.net>2019-04-15 13:31:59 -0700
commit9c69a13205151c0d801de9f9d83a818e6e8f60ec (patch)
tree32eac7d8aeb1b181e87d9c63026fc57499180273 /net/ipv6
parent789445b960c16baf626c050f762126189b45b82d (diff)
route: Avoid crash from dereferencing NULL rt->from
When __ip6_rt_update_pmtu() is called, rt->from is RCU dereferenced, but is never checked for null - rt6_flush_exceptions() may have removed the entry. [ 1913.989004] RIP: 0010:ip6_rt_cache_alloc+0x13/0x170 [ 1914.209410] Call Trace: [ 1914.214798] <IRQ> [ 1914.219226] __ip6_rt_update_pmtu+0xb0/0x190 [ 1914.228649] ip6_tnl_xmit+0x2c2/0x970 [ip6_tunnel] [ 1914.239223] ? ip6_tnl_parse_tlv_enc_lim+0x32/0x1a0 [ip6_tunnel] [ 1914.252489] ? __gre6_xmit+0x148/0x530 [ip6_gre] [ 1914.262678] ip6gre_tunnel_xmit+0x17e/0x3c7 [ip6_gre] [ 1914.273831] dev_hard_start_xmit+0x8d/0x1f0 [ 1914.283061] sch_direct_xmit+0xfa/0x230 [ 1914.291521] __qdisc_run+0x154/0x4b0 [ 1914.299407] net_tx_action+0x10e/0x1f0 [ 1914.307678] __do_softirq+0xca/0x297 [ 1914.315567] irq_exit+0x96/0xa0 [ 1914.322494] smp_apic_timer_interrupt+0x68/0x130 [ 1914.332683] apic_timer_interrupt+0xf/0x20 [ 1914.341721] </IRQ> Fixes: a68886a69180 ("net/ipv6: Make from in rt6_info rcu protected") Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@gmail.com> Reviewed-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/route.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 0302e0eb07af..7178e32eb15d 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2330,6 +2330,10 @@ static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
rcu_read_lock();
from = rcu_dereference(rt6->from);
+ if (!from) {
+ rcu_read_unlock();
+ return;
+ }
nrt6 = ip6_rt_cache_alloc(from, daddr, saddr);
if (nrt6) {
rt6_do_update_pmtu(nrt6, mtu);