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[204.195.22.127]) by smtp.gmail.com with ESMTPSA id l184sm18776155pfc.41.2019.03.18.08.57.26 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 18 Mar 2019 08:57:26 -0700 (PDT) Date: Mon, 18 Mar 2019 08:57:24 -0700 From: Stephen Hemminger To: Wang Hai Cc: , , , , , , , , , , Subject: Re: [PATCH] net-sysfs: Fix memory leak in netdev_register_kobject Message-ID: <20190318085724.1e0c017b@shemminger-XPS-13-9360> In-Reply-To: <20190319050657.61327-1-wanghai26@huawei.com> References: <20190319050657.61327-1-wanghai26@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, 19 Mar 2019 01:06:57 -0400 Wang Hai 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 > Fixes: 1d24eb4815d1 ("xps: Transmit Packet Steering") > Signed-off-by: Wang Hai > --- > 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?