linux-kernel - Re: [PATCH v3] net-sysfs: Fix memory leak in netdev_register

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Date:   Wed, 20 Mar 2019 08:34:04 -0700
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     Wang Hai <wanghai26@...wei.com>
Cc:     <davem@...emloft.net>, <idosch@...lanox.com>,
        <alexander.h.duyck@...el.com>, <tyhicks@...onical.com>,
        <f.fainelli@...il.com>, <amritha.nambiar@...el.com>,
        <joe@...ches.com>, <dmitry.torokhov@...il.com>,
        <andriy.shevchenko@...ux.intel.com>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] net-sysfs: Fix memory leak in
 netdev_register_kobject

On Wed, 20 Mar 2019 14:25:05 -0400
Wang Hai <wanghai26@...wei.com> wrote:

> When registering struct net_device, it will call
> 	register_netdevice ->
> 		netdev_register_kobject ->
> 			device_initialize(dev);
> 			dev_set_name(dev, "%s", ndev->name)
> 			device_add(dev)
> 			register_queue_kobjects(ndev)
> 
> In netdev_register_kobject(), if device_add(dev) or
> register_queue_kobjects(ndev) failed. Register_netdevice()
> will return error, causing netdev_freemem(ndev) to be
> called to free net_device, however put_device(&dev->dev)->..->
> kobject_cleanup() won't be called, 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@...wei.com>
> Fixes: 1fa5ae857bb1 ("driver core: get rid of struct device's bus_id string array")
> Signed-off-by: Wang Hai <wanghai26@...wei.com>

Looks good, thank you for fixing it. Always wonder what other bugs lurk in error
handling.

Reviewed-by: Stephen Hemminger <stephen@...workplumber.org>