4.20-stable review patch. If anyone has any objections, please let me know.
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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;