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    Subject[PATCH v3] net-sysfs: Fix memory leak in netdev_register_kobject
    Date
    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@huawei.com>
    Fixes: 1fa5ae857bb1 ("driver core: get rid of struct device's bus_id string array")
    Signed-off-by: Wang Hai <wanghai26@huawei.com>
    ---
    v2 -> v3:
    - Change kfree_const(dev->kobj.name) to put_device(dev), fix the
    problem of freeing kobj
    - Improve the description of the cause of the bug

    v1 -> v2:
    - Fix the commit id of Fixes
    - Improve the description of the cause of the bug, no code changes.
    ---
    net/core/net-sysfs.c | 14 +++++++++-----
    1 file changed, 9 insertions(+), 5 deletions(-)

    diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
    index 4ff661f..8e568422 100644
    --- a/net/core/net-sysfs.c
    +++ b/net/core/net-sysfs.c
    @@ -1745,16 +1745,20 @@ int netdev_register_kobject(struct net_device *ndev)

    error = device_add(dev);
    if (error)
    - return error;
    + goto error_put_device;

    error = register_queue_kobjects(ndev);
    - if (error) {
    - device_del(dev);
    - return error;
    - }
    + if (error)
    + goto error_device_del;

    pm_runtime_set_memalloc_noio(dev, true);

    + return 0;
    +
    +error_device_del:
    + device_del(dev);
    +error_put_device:
    + put_device(dev);
    return error;
    }

    --
    1.8.3.1
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