linux-kernel - [PATCH] driver core: Fix possible memory leak in device_link

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Date:   Thu, 30 Sep 2021 16:57:14 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     <linux-kernel@...r.kernel.org>
CC:     <rafael@...nel.org>, <gregkh@...uxfoundation.org>,
        <saravanak@...gle.com>
Subject: [PATCH] driver core: Fix possible memory leak in device_link_add()

I got memory leak as follows:

unreferenced object 0xffff88801f0b2200 (size 64):
  comm "i2c-lis2hh12-21", pid 5455, jiffies 4294944606 (age 15.224s)
  hex dump (first 32 bytes):
    72 65 67 75 6c 61 74 6f 72 3a 72 65 67 75 6c 61  regulator:regula
    74 6f 72 2e 30 2d 2d 69 32 63 3a 31 2d 30 30 31  tor.0--i2c:1-001
  backtrace:
    [<00000000bf5b0c3b>] __kmalloc_track_caller+0x19f/0x3a0
    [<0000000050da42d9>] kvasprintf+0xb5/0x150
    [<000000004bbbed13>] kvasprintf_const+0x60/0x190
    [<00000000cdac7480>] kobject_set_name_vargs+0x56/0x150
    [<00000000bf83f8e8>] dev_set_name+0xc0/0x100
    [<00000000cc1cf7e3>] device_link_add+0x6b4/0x17c0
    [<000000009db9faed>] _regulator_get+0x297/0x680
    [<00000000845e7f2b>] _devm_regulator_get+0x5b/0xe0
    [<000000003958ee25>] st_sensors_power_enable+0x71/0x1b0 [st_sensors]
    [<000000005f450f52>] st_accel_i2c_probe+0xd9/0x150 [st_accel_i2c]
    [<00000000b5f2ab33>] i2c_device_probe+0x4d8/0xbe0
    [<0000000070fb977b>] really_probe+0x299/0xc30
    [<0000000088e226ce>] __driver_probe_device+0x357/0x500
    [<00000000c21dda32>] driver_probe_device+0x4e/0x140
    [<000000004e650441>] __device_attach_driver+0x257/0x340
    [<00000000cf1891b8>] bus_for_each_drv+0x166/0x1e0

When device_register() returns an error, the name allocated in dev_set_name()
will be leaked, the put_device() should be used instead of kfree() to give up
the device reference, then the name will be freed in kobject_cleanup() and the
references of consumer and supplier will be decreased in device_link_release_fn().

Fixes: 287905e68dd2 ("driver core: Expose device link details in sysfs")
Reported-by: Hulk Robot <hulkci@...wei.com>
Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
---
 drivers/base/core.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index e65dd803a453..4a123e58711f 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -809,9 +809,7 @@ struct device_link *device_link_add(struct device *consumer,
 		     dev_bus_name(supplier), dev_name(supplier),
 		     dev_bus_name(consumer), dev_name(consumer));
 	if (device_register(&link->link_dev)) {
-		put_device(consumer);
-		put_device(supplier);
-		kfree(link);
+		put_device(&link->link_dev);
 		link = NULL;
 		goto out;
 	}
-- 
2.25.1