Messages in this thread | | | Date | Tue, 28 Sep 2021 14:11:04 +0100 | From | "Russell King (Oracle)" <> | Subject | Re: [PATCH] net: mdiobus: Fix memory leak in __mdiobus_register |
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On Sun, Sep 26, 2021 at 12:53:13PM +0800, Yanfei Xu wrote: > Once device_register() failed, we should call put_device() to > decrement reference count for cleanup. Or it will cause memory > leak. > > BUG: memory leak > unreferenced object 0xffff888114032e00 (size 256): > comm "kworker/1:3", pid 2960, jiffies 4294943572 (age 15.920s) > hex dump (first 32 bytes): > 00 00 00 00 00 00 00 00 08 2e 03 14 81 88 ff ff ................ > 08 2e 03 14 81 88 ff ff 90 76 65 82 ff ff ff ff .........ve..... > backtrace: > [<ffffffff8265cfab>] kmalloc include/linux/slab.h:591 [inline] > [<ffffffff8265cfab>] kzalloc include/linux/slab.h:721 [inline] > [<ffffffff8265cfab>] device_private_init drivers/base/core.c:3203 [inline] > [<ffffffff8265cfab>] device_add+0x89b/0xdf0 drivers/base/core.c:3253 > [<ffffffff828dd643>] __mdiobus_register+0xc3/0x450 drivers/net/phy/mdio_bus.c:537 > [<ffffffff828cb835>] __devm_mdiobus_register+0x75/0xf0 drivers/net/phy/mdio_devres.c:87 > [<ffffffff82b92a00>] ax88772_init_mdio drivers/net/usb/asix_devices.c:676 [inline] > [<ffffffff82b92a00>] ax88772_bind+0x330/0x480 drivers/net/usb/asix_devices.c:786 > [<ffffffff82baa33f>] usbnet_probe+0x3ff/0xdf0 drivers/net/usb/usbnet.c:1745 > [<ffffffff82c36e17>] usb_probe_interface+0x177/0x370 drivers/usb/core/driver.c:396 > [<ffffffff82661d17>] call_driver_probe drivers/base/dd.c:517 [inline] > [<ffffffff82661d17>] really_probe.part.0+0xe7/0x380 drivers/base/dd.c:596 > [<ffffffff826620bc>] really_probe drivers/base/dd.c:558 [inline] > [<ffffffff826620bc>] __driver_probe_device+0x10c/0x1e0 drivers/base/dd.c:751 > [<ffffffff826621ba>] driver_probe_device+0x2a/0x120 drivers/base/dd.c:781 > [<ffffffff82662a26>] __device_attach_driver+0xf6/0x140 drivers/base/dd.c:898 > [<ffffffff8265eca7>] bus_for_each_drv+0xb7/0x100 drivers/base/bus.c:427 > [<ffffffff826625a2>] __device_attach+0x122/0x260 drivers/base/dd.c:969 > [<ffffffff82660916>] bus_probe_device+0xc6/0xe0 drivers/base/bus.c:487 > [<ffffffff8265cd0b>] device_add+0x5fb/0xdf0 drivers/base/core.c:3359 > [<ffffffff82c343b9>] usb_set_configuration+0x9d9/0xb90 drivers/usb/core/message.c:2170 > [<ffffffff82c4473c>] usb_generic_driver_probe+0x8c/0xc0 drivers/usb/core/generic.c:238 > > BUG: memory leak > unreferenced object 0xffff888116f06900 (size 32): > comm "kworker/0:2", pid 2670, jiffies 4294944448 (age 7.160s) > hex dump (first 32 bytes): > 75 73 62 2d 30 30 31 3a 30 30 33 00 00 00 00 00 usb-001:003..... > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > backtrace: > [<ffffffff81484516>] kstrdup+0x36/0x70 mm/util.c:60 > [<ffffffff814845a3>] kstrdup_const+0x53/0x80 mm/util.c:83 > [<ffffffff82296ba2>] kvasprintf_const+0xc2/0x110 lib/kasprintf.c:48 > [<ffffffff82358d4b>] kobject_set_name_vargs+0x3b/0xe0 lib/kobject.c:289 > [<ffffffff826575f3>] dev_set_name+0x63/0x90 drivers/base/core.c:3147 > [<ffffffff828dd63b>] __mdiobus_register+0xbb/0x450 drivers/net/phy/mdio_bus.c:535 > [<ffffffff828cb835>] __devm_mdiobus_register+0x75/0xf0 drivers/net/phy/mdio_devres.c:87 > [<ffffffff82b92a00>] ax88772_init_mdio drivers/net/usb/asix_devices.c:676 [inline] > [<ffffffff82b92a00>] ax88772_bind+0x330/0x480 drivers/net/usb/asix_devices.c:786 > [<ffffffff82baa33f>] usbnet_probe+0x3ff/0xdf0 drivers/net/usb/usbnet.c:1745 > [<ffffffff82c36e17>] usb_probe_interface+0x177/0x370 drivers/usb/core/driver.c:396 > [<ffffffff82661d17>] call_driver_probe drivers/base/dd.c:517 [inline] > [<ffffffff82661d17>] really_probe.part.0+0xe7/0x380 drivers/base/dd.c:596 > [<ffffffff826620bc>] really_probe drivers/base/dd.c:558 [inline] > [<ffffffff826620bc>] __driver_probe_device+0x10c/0x1e0 drivers/base/dd.c:751 > [<ffffffff826621ba>] driver_probe_device+0x2a/0x120 drivers/base/dd.c:781 > [<ffffffff82662a26>] __device_attach_driver+0xf6/0x140 drivers/base/dd.c:898 > [<ffffffff8265eca7>] bus_for_each_drv+0xb7/0x100 drivers/base/bus.c:427 > [<ffffffff826625a2>] __device_attach+0x122/0x260 drivers/base/dd.c:969 > > Reported-by: syzbot+398e7dc692ddbbb4cfec@syzkaller.appspotmail.com > Signed-off-by: Yanfei Xu <yanfei.xu@windriver.com> > --- > drivers/net/phy/mdio_bus.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c > index 53f034fc2ef7..6f4b4e5df639 100644 > --- a/drivers/net/phy/mdio_bus.c > +++ b/drivers/net/phy/mdio_bus.c > @@ -537,6 +537,7 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner) > err = device_register(&bus->dev); > if (err) { > pr_err("mii_bus %s failed to register\n", bus->id); > + put_device(&bus->dev); > return -EINVAL; > }
This patch is incorrect:
1) the reported failure does not involve this path. 2) device_register() failing does not need a put_device() because the contained device_add() undoes everything that it attempted to do.
The above backtraces occur because we have had a successful device_register() fall, but later call device_del() and then kfree() the mdiobus, which has an embedded the struct device that has pointers to memory that has not been cleaned up - because kfree() is the wrong way to handle this.
bus->state needs to be set to indicate that the embedded struct device has been registered but no longer is registered if we fail after device_register() has been called.
If device_register() fails, then there is no problem.
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