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From: Junjie Cao <junjie.cao@intel.com>
To: pabeni@redhat.com, davem@davemloft.net, edumazet@google.com,
	kuba@kernel.org,
	syzbot+14afda08dc3484d5db82@syzkaller.appspotmail.com
Cc: horms@kernel.org, linux-hams@vger.kernel.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	syzkaller-bugs@googlegroups.com, stable@vger.kernel.org,
	junjie.cao@intel.com
Subject: [PATCH 2/2] netrom: fix reference count leak in nr_rt_device_down
Date: Thu,  4 Dec 2025 17:09:05 +0800	[thread overview]
Message-ID: <20251204090905.28663-3-junjie.cao@intel.com> (raw)
In-Reply-To: <20251204090905.28663-1-junjie.cao@intel.com>

When a device goes down, nr_rt_device_down() clears the routes that
use this device. However, it fails to drop the per-route reference to
the neighbour (nr_neigh): neither nr_neigh->count nor its refcount
is decremented when the route is removed.

Mirror the behaviour of nr_dec_obs() / nr_del_node() by decrementing
nr_neigh->count and calling nr_neigh_put(), so that the neighbour
reference is properly released when a device goes down.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Junjie Cao <junjie.cao@intel.com>
---
 net/netrom/nr_route.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/netrom/nr_route.c b/net/netrom/nr_route.c
index 20aacfdfccd4..35d10985fd7a 100644
--- a/net/netrom/nr_route.c
+++ b/net/netrom/nr_route.c
@@ -517,6 +517,9 @@ void nr_rt_device_down(struct net_device *dev)
 		for (i = 0; i < t->count; i++) {
 			s = t->routes[i].neighbour;
 			if (s->dev == dev) {
+				s->count--;
+				nr_neigh_put(s);
+
 				t->count--;
 
 				switch (i) {
-- 
2.43.0


      parent reply	other threads:[~2025-12-04  9:09 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-12-04  9:09 [PATCH v2 0/2] netrom: fix deadlock and refcount leak in nr_rt_device_down Junjie Cao
2025-12-04  9:09 ` [PATCH 1/2] netrom: fix possible deadlock " Junjie Cao
2026-01-02 20:46   ` Jakub Kicinski
2025-12-04  9:09 ` Junjie Cao [this message]

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