memory leak in cfserl_create

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    788a0249 Merge tag 'arc-5.2-rc4' of git://git.kernel.org/p..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=123efa5aa00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d5c73825cbdc7326
dashboard link: https://syzkaller.appspot.com/bug?extid=7ec324747ce876a29db6
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=171ca536a00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+7ec324747ce876a29db6@xxxxxxxxxxxxxxxxxxxxxxxxx

TDEV_CHANGE): hsr_slave_1: link becomes ready
2019/06/05 07:03:42 executed programs: 14
2019/06/05 07:03:48 executed programs: 15
2019/06/05 07:03:56 executed programs: 30
BUG: memory leak
unreferenced object 0xffff88810d22ca00 (size 128):
  comm "syz-executor.1", pid 7571, jiffies 4294948034 (age 9.460s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000d4b3552e>] kmemleak_alloc_recursive  
include/linux/kmemleak.h:55 [inline]
    [<00000000d4b3552e>] slab_post_alloc_hook mm/slab.h:439 [inline]
    [<00000000d4b3552e>] slab_alloc mm/slab.c:3326 [inline]
    [<00000000d4b3552e>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
    [<00000000409297cb>] kmalloc include/linux/slab.h:547 [inline]
    [<00000000409297cb>] kzalloc include/linux/slab.h:742 [inline]
    [<00000000409297cb>] cfserl_create+0x24/0x76 net/caif/cfserl.c:36
    [<000000000b6ebed9>] caif_device_notify+0x347/0x3bc  
net/caif/caif_dev.c:388
    [<0000000052e58523>] notifier_call_chain+0x66/0xb0 kernel/notifier.c:95
    [<0000000016b2101e>] __raw_notifier_call_chain kernel/notifier.c:396  
[inline]
    [<0000000016b2101e>] raw_notifier_call_chain+0x2e/0x40  
kernel/notifier.c:403
    [<0000000041e2ecf0>] call_netdevice_notifiers_info+0x33/0x70  
net/core/dev.c:1749
    [<00000000f45634e0>] call_netdevice_notifiers_extack  
net/core/dev.c:1761 [inline]
    [<00000000f45634e0>] call_netdevice_notifiers net/core/dev.c:1775  
[inline]
    [<00000000f45634e0>] register_netdevice+0x445/0x600 net/core/dev.c:8734
    [<0000000043f37c7e>] ldisc_open+0x1f7/0x350  
drivers/net/caif/caif_serial.c:359
    [<0000000048b48475>] tty_ldisc_open.isra.0+0x40/0x70  
drivers/tty/tty_ldisc.c:469
    [<000000001b540e53>] tty_set_ldisc+0x149/0x240  
drivers/tty/tty_ldisc.c:596
    [<00000000987d85c0>] tiocsetd drivers/tty/tty_io.c:2332 [inline]
    [<00000000987d85c0>] tty_ioctl+0x366/0xa30 drivers/tty/tty_io.c:2592
    [<00000000bdb74dbb>] vfs_ioctl fs/ioctl.c:46 [inline]
    [<00000000bdb74dbb>] file_ioctl fs/ioctl.c:509 [inline]
    [<00000000bdb74dbb>] do_vfs_ioctl+0x62a/0x810 fs/ioctl.c:696
    [<0000000021ef067c>] ksys_ioctl+0x86/0xb0 fs/ioctl.c:713
    [<00000000d1d65c38>] __do_sys_ioctl fs/ioctl.c:720 [inline]
    [<00000000d1d65c38>] __se_sys_ioctl fs/ioctl.c:718 [inline]
    [<00000000d1d65c38>] __x64_sys_ioctl+0x1e/0x30 fs/ioctl.c:718
    [<000000001056684e>] do_syscall_64+0x76/0x1a0  
arch/x86/entry/common.c:301
    [<0000000010a5606e>] entry_SYSCALL_64_after_hwframe+0x44/0xa9



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