From: Florian Fainelli f.fainelli@gmail.com
[ Upstream commit 8dbe4c5d5e40fe140221024f7b16bec9f310bf70 ]
of_find_node_by_name() will do an of_node_put() on the "from" argument. With CONFIG_OF_DYNAMIC enabled which checks for device_node reference counts, we would be getting a warning like this:
[ 6.347230] refcount_t: increment on 0; use-after-free. [ 6.352498] WARNING: CPU: 3 PID: 77 at lib/refcount.c:156 refcount_inc_checked+0x38/0x44 [ 6.360601] Modules linked in: [ 6.363661] CPU: 3 PID: 77 Comm: kworker/3:1 Tainted: G W 5.4.46-gb78b3e9956e6 #13 [ 6.372546] Hardware name: BCM97278SV (DT) [ 6.376649] Workqueue: events deferred_probe_work_func [ 6.381796] pstate: 60000005 (nZCv daif -PAN -UAO) [ 6.386595] pc : refcount_inc_checked+0x38/0x44 [ 6.391133] lr : refcount_inc_checked+0x38/0x44 ... [ 6.478791] Call trace: [ 6.481243] refcount_inc_checked+0x38/0x44 [ 6.485433] kobject_get+0x3c/0x4c [ 6.488840] of_node_get+0x24/0x34 [ 6.492247] of_irq_find_parent+0x3c/0xe0 [ 6.496263] of_irq_parse_one+0xe4/0x1d0 [ 6.500191] irq_of_parse_and_map+0x44/0x84 [ 6.504381] bcm_sf2_sw_probe+0x22c/0x844 [ 6.508397] platform_drv_probe+0x58/0xa8 [ 6.512413] really_probe+0x238/0x3fc [ 6.516081] driver_probe_device+0x11c/0x12c [ 6.520358] __device_attach_driver+0xa8/0x100 [ 6.524808] bus_for_each_drv+0xb4/0xd0 [ 6.528650] __device_attach+0xd0/0x164 [ 6.532493] device_initial_probe+0x24/0x30 [ 6.536682] bus_probe_device+0x38/0x98 [ 6.540524] deferred_probe_work_func+0xa8/0xd4 [ 6.545061] process_one_work+0x178/0x288 [ 6.549078] process_scheduled_works+0x44/0x48 [ 6.553529] worker_thread+0x218/0x270 [ 6.557285] kthread+0xdc/0xe4 [ 6.560344] ret_from_fork+0x10/0x18 [ 6.563925] ---[ end trace 68f65caf69bb152a ]---
Fix this by adding a of_node_get() to increment the reference count prior to the call.
Fixes: afa3b592953b ("net: dsa: bcm_sf2: Ensure correct sub-node is parsed") Signed-off-by: Florian Fainelli f.fainelli@gmail.com Reviewed-by: Andrew Lunn andrew@lunn.ch Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/dsa/bcm_sf2.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/net/dsa/bcm_sf2.c b/drivers/net/dsa/bcm_sf2.c index ccba648452c4..c0bba680d4a8 100644 --- a/drivers/net/dsa/bcm_sf2.c +++ b/drivers/net/dsa/bcm_sf2.c @@ -1078,6 +1078,8 @@ static int bcm_sf2_sw_probe(struct platform_device *pdev) set_bit(0, priv->cfp.used); set_bit(0, priv->cfp.unique);
+ /* Balance of_node_put() done by of_find_node_by_name() */ + of_node_get(dn); ports = of_find_node_by_name(dn, "ports"); if (ports) { bcm_sf2_identify_ports(priv, ports);