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Subject[PATCH 4.20 138/183] geneve: should not call rt6_lookup() when ipv6 was disabled
Date
4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hangbin Liu <liuhangbin@gmail.com>

[ Upstream commit c0a47e44c0980b3b23ee31fa7936d70ea5dce491 ]

When we add a new GENEVE device with IPv6 remote, checking only for
IS_ENABLED(CONFIG_IPV6) is not enough as we may disable IPv6 in the
kernel command line (ipv6.disable=1), and calling rt6_lookup() would
cause a NULL pointer dereference.

v2:
- don't mix declarations and code (reported by Stefano Brivio, Eric Dumazet)
- there's no need to use in6_dev_get() as we only need to check that
idev exists (reported by David Ahern). This is under RTNL, so we can
simply use __in6_dev_get() instead (Stefano, Eric).

Reported-by: Jianlin Shi <jishi@redhat.com>
Fixes: c40e89fd358e9 ("geneve: configure MTU based on a lower device")
Cc: Alexey Kodanev <alexey.kodanev@oracle.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/geneve.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -1426,9 +1426,13 @@ static void geneve_link_config(struct ne
}
#if IS_ENABLED(CONFIG_IPV6)
case AF_INET6: {
- struct rt6_info *rt = rt6_lookup(geneve->net,
- &info->key.u.ipv6.dst, NULL, 0,
- NULL, 0);
+ struct rt6_info *rt;
+
+ if (!__in6_dev_get(dev))
+ break;
+
+ rt = rt6_lookup(geneve->net, &info->key.u.ipv6.dst, NULL, 0,
+ NULL, 0);

if (rt && rt->dst.dev)
ldev_mtu = rt->dst.dev->mtu - GENEVE_IPV6_HLEN;

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