| Message ID | 55e9785e2ae2eae03c4af850a07e3297c5a0b784.1632861239.git.paskripkin@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v2,1/2] Revert "net: mdiobus: Fix memory leak in __mdiobus_register" | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Guessing tree name failed - patch did not apply |
On Tue, Sep 28, 2021 at 11:40:15PM +0300, Pavel Skripkin wrote: > Syzbot reported memory leak in MDIO bus interface, the problem was in > wrong state logic. > > MDIOBUS_ALLOCATED indicates 2 states: > 1. Bus is only allocated > 2. Bus allocated and __mdiobus_register() fails, but > device_register() was called > > In case of device_register() has been called we should call put_device() > to correctly free the memory allocated for this device, but mdiobus_free() > calls just kfree(dev) in case of MDIOBUS_ALLOCATED state > > To avoid this behaviour we need to set bus->state to MDIOBUS_UNREGISTERED > _before_ calling device_register(), because put_device() should be > called even in case of device_register() failure. > > Link: https://lore.kernel.org/netdev/YVMRWNDZDUOvQjHL@shell.armlinux.org.uk/ > Fixes: 46abc02175b3 ("phylib: give mdio buses a device tree presence") > Reported-and-tested-by: syzbot+398e7dc692ddbbb4cfec@syzkaller.appspotmail.com > Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> Thanks! Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com> regards, dan carpenter
On Tue, 28 Sep 2021 23:40:15 +0300 Pavel Skripkin wrote: > + /* We need to set state to MDIOBUS_UNREGISTERED to correctly realese > + * the device in mdiobus_free() > + * > + * State will be updated later in this function in case of success > + */ > + bus->state == MDIOBUS_UNREGISTERED; IDK how syzbot has tested it but clearly we should blindly depend on that. s/==/=/ Compiler would have told you this.
On 9/30/21 02:48, Jakub Kicinski wrote: > On Tue, 28 Sep 2021 23:40:15 +0300 Pavel Skripkin wrote: >> + /* We need to set state to MDIOBUS_UNREGISTERED to correctly realese >> + * the device in mdiobus_free() >> + * >> + * State will be updated later in this function in case of success >> + */ >> + bus->state == MDIOBUS_UNREGISTERED; > > IDK how syzbot has tested it but clearly we should blindly > depend on that. > > s/==/=/ > > Compiler would have told you this. > whooops... sorry about that. syzbot has tested v1. v2 is same, but without new state (so, the logic in v1 and v2 is the same). I guess, it's copy-paste error on my side :). Will send v3 this evening With regards, Pavel Skripkin
diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c index 53f034fc2ef7..2d16a93af1ae 100644 --- a/drivers/net/phy/mdio_bus.c +++ b/drivers/net/phy/mdio_bus.c @@ -534,6 +534,13 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner) bus->dev.groups = NULL; dev_set_name(&bus->dev, "%s", bus->id); + /* We need to set state to MDIOBUS_UNREGISTERED to correctly realese + * the device in mdiobus_free() + * + * State will be updated later in this function in case of success + */ + bus->state == MDIOBUS_UNREGISTERED; + err = device_register(&bus->dev); if (err) { pr_err("mii_bus %s failed to register\n", bus->id);
Syzbot reported memory leak in MDIO bus interface, the problem was in wrong state logic. MDIOBUS_ALLOCATED indicates 2 states: 1. Bus is only allocated 2. Bus allocated and __mdiobus_register() fails, but device_register() was called In case of device_register() has been called we should call put_device() to correctly free the memory allocated for this device, but mdiobus_free() calls just kfree(dev) in case of MDIOBUS_ALLOCATED state To avoid this behaviour we need to set bus->state to MDIOBUS_UNREGISTERED _before_ calling device_register(), because put_device() should be called even in case of device_register() failure. Link: https://lore.kernel.org/netdev/YVMRWNDZDUOvQjHL@shell.armlinux.org.uk/ Fixes: 46abc02175b3 ("phylib: give mdio buses a device tree presence") Reported-and-tested-by: syzbot+398e7dc692ddbbb4cfec@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> --- Changes in v2: Removed new state, since MDIOBUS_UNREGISTERED can be used. Also, moved bus->state initialization _before_ device_register() call, because Yanfei's patch is reverted in [v2 1/2] --- drivers/net/phy/mdio_bus.c | 7 +++++++ 1 file changed, 7 insertions(+)