[PATCH 6.6.y 3/3] net: phonet: free phonet_device after RCU grace period

[Sasha Levin <sashal@kernel.org>]

From: Santosh Kalluri <santosh.kalluri129@gmail.com>

[ Upstream commit 71de0177b28da751f407581a4515cf4d762f6296 ]

phonet_device_destroy() removes a phonet_device from the per-net device
list with list_del_rcu(), but frees it immediately. RCU readers walking
the same list can still hold a pointer to the object after it has been
removed, leading to a slab-use-after-free.

Use kfree_rcu(), matching the lifetime rule already used by
phonet_address_del() for the same object type.

Fixes: eeb74a9d45f7 ("Phonet: convert devices list to RCU")
Cc: stable@vger.kernel.org
Signed-off-by: Santosh Kalluri <santosh.kalluri129@gmail.com>
Acked-by: Rémi Denis-Courmont <remi@remlab.net>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/phonet/pn_dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/phonet/pn_dev.c b/net/phonet/pn_dev.c
index 2e7d850dc72668..3f020c362d6cde 100644
--- a/net/phonet/pn_dev.c
+++ b/net/phonet/pn_dev.c
@@ -105,7 +105,7 @@ static void phonet_device_destroy(struct net_device *dev)
 		for_each_set_bit(addr, pnd->addrs, 64)
 			phonet_address_notify(net, RTM_DELADDR, ifindex, addr);
 
-		kfree(pnd);
+		kfree_rcu(pnd, rcu);
 	}
 }
 
-- 
2.53.0