[PATCH rdma-next 5/6] RDMA/cma: Protect ifindex access during IPv6 route lookup

[Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

From: Parav Pandit <parav-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>

Netdev ifindex can change while performing IPv6 rt6_lookup().
Therefore access ifindex under rcu lock.
This ensures that ifindex won't change while lookup is in progress.

Fixes: f887f2ac87c2 ("IB/cma: Validate routing of incoming requests")
Reviewed-by: Daniel Jurgens <danielj-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Signed-off-by: Parav Pandit <parav-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Signed-off-by: Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
 drivers/infiniband/core/cma.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 90dead30de4c..690ed4238d72 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -1333,11 +1333,15 @@ static bool validate_ipv6_net_dev(struct net_device *net_dev,
 #if IS_ENABLED(CONFIG_IPV6)
 	const int strict = ipv6_addr_type(&dst_addr->sin6_addr) &
 			   IPV6_ADDR_LINKLOCAL;
-	struct rt6_info *rt = rt6_lookup(dev_net(net_dev), &dst_addr->sin6_addr,
-					 &src_addr->sin6_addr, net_dev->ifindex,
-					 strict);
+	struct rt6_info *rt;
 	bool ret;
 
+	rcu_read_lock();
+	rt = rt6_lookup(dev_net(net_dev), &dst_addr->sin6_addr,
+			&src_addr->sin6_addr, net_dev->ifindex,
+			strict);
+	rcu_read_unlock();
+
 	if (!rt)
 		return false;
 
-- 
2.15.1

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