linux-kernel - [PATCH] mfd: max8998: fix potential double free in probe

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Date:   Tue, 22 Sep 2020 11:14:16 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     Mark Brown <broonie@...nsource.wolfsonmicro.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Samuel Ortiz <sameo@...ux.intel.com>,
        Liam Girdwood <lrg@...mlogic.co.uk>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH] mfd: max8998: fix potential double free in probe

The problem is that mfd_add_devices() calls mfd_remove_devices() on
failure and then the probe function will also call mfd_remove_devices().
I don't know exactly what problems this will cause but I'm pretty sure
that it will trigger the BUG_ON() at the start of ida_free().

One thing that this patch changes is that it adds a check for if
max8998_irq_init() fails.

Fixes: 156f252857df ("drivers: regulator: add Maxim 8998 driver")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
Checking max8998_irq_init() is slightly risky because sometimes these
functions have been failing and we didn't know.

 drivers/mfd/max8998.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/mfd/max8998.c b/drivers/mfd/max8998.c
index 785f8e9841b7..9713c3ea4a63 100644
--- a/drivers/mfd/max8998.c
+++ b/drivers/mfd/max8998.c
@@ -202,7 +202,9 @@ static int max8998_i2c_probe(struct i2c_client *i2c,
 	}
 	i2c_set_clientdata(max8998->rtc, max8998);
 
-	max8998_irq_init(max8998);
+	ret = max8998_irq_init(max8998);
+	if (ret)
+		goto unregister_dummy;
 
 	pm_runtime_set_active(max8998->dev);
 
@@ -222,15 +224,15 @@ static int max8998_i2c_probe(struct i2c_client *i2c,
 	}
 
 	if (ret < 0)
-		goto err;
+		goto release_irq;
 
 	device_init_wakeup(max8998->dev, max8998->wakeup);
 
-	return ret;
+	return 0;
 
-err:
-	mfd_remove_devices(max8998->dev);
+release_irq:
 	max8998_irq_exit(max8998);
+unregister_dummy:
 	i2c_unregister_device(max8998->rtc);
 	return ret;
 }
-- 
2.28.0