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>
Signed-off-by: Jonathan Lemon <jonathan.le...@gmail.com>
---
net/ipv6/route.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index d555edaaff13..b9cbe6815f2c 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2331,6 +2331,10 @@ 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);
--
2.17.1
