Messages in this thread | | | Subject | Re: [PATCH] net-sysfs: Fix memory leak in netdev_register_kobject | From | "wanghai (M)" <> | Date | Tue, 19 Mar 2019 11:39:54 +0800 |
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在 2019/3/19 11:15, Stephen Hemminger 写道: > On Tue, 19 Mar 2019 11:03:54 +0800 > "wanghai (M)" <wanghai26@huawei.com> wrote: > >> 在 2019/3/18 23:57, Stephen Hemminger 写道: >>> On Tue, 19 Mar 2019 01:06:57 -0400 >>> Wang Hai <wanghai26@huawei.com> wrote: >>> >>>> When registering struct net_device, it will call >>>> register_netdevice -> >>>> netdev_register_kobject -> >>>> device_add(dev) >>>> register_queue_kobjects(ndev) >>>> >>>> If device_add(dev) or register_queue_kobjects(ndev) fails. >>>> Register_netdevice() will return error, causing netdev_freemem(ndev) >>>> to be called to free net_device, however (&ndev->dev)->kobj.name will >>>> not be freed, resulting in a memory leak. >>>> >>>> syzkaller report this: >>>> BUG: memory leak >>>> unreferenced object 0xffff8881f4fad168 (size 8): >>>> comm "syz-executor.0", pid 3575, jiffies 4294778002 (age 20.134s) >>>> hex dump (first 8 bytes): >>>> 77 70 61 6e 30 00 ff ff wpan0... >>>> backtrace: >>>> [<000000006d2d91d7>] kstrdup_const+0x3d/0x50 mm/util.c:73 >>>> [<00000000ba9ff953>] kvasprintf_const+0x112/0x170 lib/kasprintf.c:48 >>>> [<000000005555ec09>] kobject_set_name_vargs+0x55/0x130 lib/kobject.c:281 >>>> [<0000000098d28ec3>] dev_set_name+0xbb/0xf0 drivers/base/core.c:1915 >>>> [<00000000b7553017>] netdev_register_kobject+0xc0/0x410 net/core/net-sysfs.c:1727 >>>> [<00000000c826a797>] register_netdevice+0xa51/0xeb0 net/core/dev.c:8711 >>>> [<00000000857bfcfd>] cfg802154_update_iface_num.isra.2+0x13/0x90 [ieee802154] >>>> [<000000003126e453>] ieee802154_llsec_fill_key_id+0x1d5/0x570 [ieee802154] >>>> [<00000000e4b3df51>] 0xffffffffc1500e0e >>>> [<00000000b4319776>] platform_drv_probe+0xc6/0x180 drivers/base/platform.c:614 >>>> [<0000000037669347>] really_probe+0x491/0x7c0 drivers/base/dd.c:509 >>>> [<000000008fed8862>] driver_probe_device+0xdc/0x240 drivers/base/dd.c:671 >>>> [<00000000baf52041>] device_driver_attach+0xf2/0x130 drivers/base/dd.c:945 >>>> [<00000000c7cc8dec>] __driver_attach+0x10e/0x210 drivers/base/dd.c:1022 >>>> [<0000000057a757c2>] bus_for_each_dev+0x154/0x1e0 drivers/base/bus.c:304 >>>> [<000000005f5ae04b>] bus_add_driver+0x427/0x5e0 drivers/base/bus.c:645 >>>> >>>> Reported-by: Hulk Robot <hulkci@huawei.com> >>>> Fixes: 1d24eb4815d1 ("xps: Transmit Packet Steering") >>>> Signed-off-by: Wang Hai <wanghai26@huawei.com> >>>> --- >>>> net/core/net-sysfs.c | 15 ++++++++++----- >>>> 1 file changed, 10 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c >>>> index 4ff661f..f0e53dc 100644 >>>> --- a/net/core/net-sysfs.c >>>> +++ b/net/core/net-sysfs.c >>>> @@ -1745,17 +1745,22 @@ int netdev_register_kobject(struct net_device *ndev) >>>> >>>> error = device_add(dev); >>>> if (error) >>>> - return error; >>>> + goto device_add_error; >>>> >>>> error = register_queue_kobjects(ndev); >>>> - if (error) { >>>> - device_del(dev); >>>> - return error; >>>> - } >>>> + if (error) >>>> + goto register_error; >>>> >>>> pm_runtime_set_memalloc_noio(dev, true); >>>> >>>> +out: >>>> return error; >>>> + >>>> +register_error: >>>> + device_del(dev); >>>> +device_add_error: >>>> + kfree_const(dev->kobj.name); >>> This looks a bug in device_add() not here. >>> In general, it is better for an api to clean up after itself. >>> Since dev->kobj.name is created in device_add and normally freed >>> in device_del; why is device_add leaving it behind?\ >> When registering struct net_device, it will call >> register_netdevice -> >> netdev_register_kobject -> >> dev_set_name(dev, "%s", ndev->name) >> device_add(dev) >> register_queue_kobjects(ndev) >> >> The dev->kobj.name that causes the memory leak is created in >> dev_set_name(dev, "%s", ndev-> name) in the function >> netdev_register_kobject(), not in device_add(dev). If device_add(dev) or >> register_queue_kobjects(ndev) fails, it should release dev-> kobj.name >> in netdev_register_kobject() > Good catch, dev_set_name is using asprintf to allocate new memory > for the name. The problem with your patch is that device_del() > already cleans up the device (including name). The device object > should really not be touched after device_del. > > Where is the name freed in the normal case? > > > . Device_del just delete device from system, but do not clean up dev->kobj.name. In normal case, the name is freed in free_netdev(dev)->put_device(&dev->dev)->kobject_put(&dev->kobj)->kobject_cleanup() ,not in device_del()
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