[PATCH] net: fec: fix ref count leaking when pm_runtime_get_sync fails

[PATCH] net: fec: fix ref count leaking when pm_runtime_get_sync fails

[Navid Emamdoost]

in fec_enet_mdio_read, fec_enet_mdio_write, fec_enet_get_regs,
fec_enet_open and fec_drv_remove, pm_runtime_get_sync is called which
increments the counter even in case of failure, leading to incorrect
ref count. In case of failure, decrement the ref count before returning.

Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
---
 drivers/net/ethernet/freescale/fec_main.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index dc6f8763a5d4..a33012b89cc9 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1827,8 +1827,10 @@ static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
 	bool is_c45 = !!(regnum & MII_ADDR_C45);
 
 	ret = pm_runtime_get_sync(dev);
-	if (ret < 0)
+	if (ret < 0) {
+		pm_runtime_put_autosuspend(dev);
 		return ret;
+	}
 
 	reinit_completion(&fep->mdio_done);
 
@@ -1893,8 +1895,10 @@ static int fec_enet_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
 	bool is_c45 = !!(regnum & MII_ADDR_C45);
 
 	ret = pm_runtime_get_sync(dev);
-	if (ret < 0)
+	if (ret < 0) {
+		pm_runtime_put_autosuspend(dev);
 		return ret;
+	}
 	else
 		ret = 0;
 
@@ -2258,7 +2262,7 @@ static void fec_enet_get_regs(struct net_device *ndev,
 
 	ret = pm_runtime_get_sync(dev);
 	if (ret < 0)
-		return;
+		goto out;
 
 	regs->version = fec_enet_register_version;
 
@@ -2276,6 +2280,7 @@ static void fec_enet_get_regs(struct net_device *ndev,
 	}
 
 	pm_runtime_mark_last_busy(dev);
+out:
 	pm_runtime_put_autosuspend(dev);
 }
 
@@ -2952,8 +2957,10 @@ fec_enet_open(struct net_device *ndev)
 	bool reset_again;
 
 	ret = pm_runtime_get_sync(&fep->pdev->dev);
-	if (ret < 0)
+	if (ret < 0) {
+		pm_runtime_put_autosuspend(&fep->pdev->dev);
 		return ret;
+	}
 
 	pinctrl_pm_select_default_state(&fep->pdev->dev);
 	ret = fec_enet_clk_enable(ndev, true);
@@ -3741,8 +3748,10 @@ fec_drv_remove(struct platform_device *pdev)
 	int ret;
 
 	ret = pm_runtime_get_sync(&pdev->dev);
-	if (ret < 0)
+	if (ret < 0) {
+		pm_runtime_put_noidle(&pdev->dev);
 		return ret;
+	}
 
 	cancel_work_sync(&fep->tx_timeout_work);
 	fec_ptp_stop(pdev);
-- 
2.17.1

Re: [PATCH] net: fec: fix ref count leaking when pm_runtime_get_sync fails

[David Miller]

From: Navid Emamdoost <navid.emamdoost@gmail.com>
Date: Sun, 14 Jun 2020 00:38:01 -0500

> in fec_enet_mdio_read, fec_enet_mdio_write, fec_enet_get_regs,
> fec_enet_open and fec_drv_remove, pm_runtime_get_sync is called which
> increments the counter even in case of failure, leading to incorrect
> ref count. In case of failure, decrement the ref count before returning.
> 
> Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>

This does not apply to the net tree.

RE: [EXT] Re: [PATCH] net: fec: fix ref count leaking when pm_runtime_get_sync fails

[Andy Duan]

From: David Miller <davem@davemloft.net> Sent: Tuesday, June 16, 2020 4:42 AM
> From: Navid Emamdoost <navid.emamdoost@gmail.com>
> Date: Sun, 14 Jun 2020 00:38:01 -0500
> 
> > in fec_enet_mdio_read, fec_enet_mdio_write, fec_enet_get_regs,
> > fec_enet_open and fec_drv_remove, pm_runtime_get_sync is called which
> > increments the counter even in case of failure, leading to incorrect
> > ref count. In case of failure, decrement the ref count before returning.
> >
> > Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
> 
> This does not apply to the net tree.

Wolfram Sang wonder if such de-reference can be better handled by pm runtime core code.
https://lkml.org/lkml/2020/6/14/76