memory leak in fdb_create

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    abf02e29 Merge tag 'pm-5.2-rc6' of git://git.kernel.org/pu..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12970eb2a00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=56f1da14935c3cce
dashboard link: https://syzkaller.appspot.com/bug?extid=88533dc8b582309bf3ee
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16de5c06a00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10546026a00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+88533dc8b582309bf3ee@xxxxxxxxxxxxxxxxxxxxxxxxx

ffffffffda RBX: 0000000000000000 RCX: 0000000000441519
BUG: memory leak
unreferenced object 0xffff888123886800 (size 128):
  comm "softirq", pid 0, jiffies 4294945699 (age 13.160s)
  hex dump (first 32 bytes):
    81 89 f8 20 81 88 ff ff 00 00 00 00 00 00 00 00  ... ............
    32 f9 fc b7 11 e2 01 00 00 00 00 00 00 00 00 00  2...............
  backtrace:
    [<00000000ca2421fa>] kmemleak_alloc_recursive  
include/linux/kmemleak.h:43 [inline]
    [<00000000ca2421fa>] slab_post_alloc_hook mm/slab.h:439 [inline]
    [<00000000ca2421fa>] slab_alloc mm/slab.c:3326 [inline]
    [<00000000ca2421fa>] kmem_cache_alloc+0x134/0x270 mm/slab.c:3488
    [<000000007faade68>] fdb_create+0x49/0x5a0 net/bridge/br_fdb.c:492
    [<00000000772dfc36>] fdb_insert+0xb7/0x100 net/bridge/br_fdb.c:536
    [<00000000ded35dd0>] br_fdb_insert+0x3b/0x60 net/bridge/br_fdb.c:552
    [<00000000758ae277>] __vlan_add+0x617/0xdf0 net/bridge/br_vlan.c:284
    [<0000000054c3b165>] br_vlan_add+0x26f/0x480 net/bridge/br_vlan.c:678
    [<00000000ed895462>] br_vlan_init+0xe9/0x130 net/bridge/br_vlan.c:1061
    [<00000000f916c753>] br_dev_init+0xa6/0x170 net/bridge/br_device.c:137
    [<00000000a4e1a1ea>] register_netdevice+0xbf/0x600 net/core/dev.c:8663
    [<00000000bdcf4ebd>] register_netdev+0x24/0x40 net/core/dev.c:8851
    [<0000000042e6c0c4>] br_add_bridge+0x5e/0xa0 net/bridge/br_if.c:456
    [<0000000036402409>] br_ioctl_deviceless_stub+0x30c/0x350  
net/bridge/br_ioctl.c:374
    [<00000000e57c9a76>] sock_ioctl+0x287/0x480 net/socket.c:1141
    [<00000000109b8329>] vfs_ioctl fs/ioctl.c:46 [inline]
    [<00000000109b8329>] file_ioctl fs/ioctl.c:509 [inline]
    [<00000000109b8329>] do_vfs_ioctl+0x62a/0x810 fs/ioctl.c:696
    [<00000000d8eb5a5e>] ksys_ioctl+0x86/0xb0 fs/ioctl.c:713
    [<00000000cd162915>] __do_sys_ioctl fs/ioctl.c:720 [inline]
    [<00000000cd162915>] __se_sys_ioctl fs/ioctl.c:718 [inline]
    [<00000000cd162915>] __x64_sys_ioctl+0x1e/0x30 fs/ioctl.c:718

BUG: memory leak
unreferenced object 0xffff88811ced2de0 (size 32):
  comm "syz-executor140", pid 6998, jiffies 4294945699 (age 13.160s)
  hex dump (first 32 bytes):
    d3 d2 f1 a7 6c 83 5b 30 30 15 a1 6f 77 3f 00 00  ....l.[00..ow?..
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000d53fdc1e>] kmemleak_alloc_recursive  
include/linux/kmemleak.h:43 [inline]
    [<00000000d53fdc1e>] slab_post_alloc_hook mm/slab.h:439 [inline]
    [<00000000d53fdc1e>] slab_alloc mm/slab.c:3326 [inline]
    [<00000000d53fdc1e>] __do_kmalloc mm/slab.c:3658 [inline]
    [<00000000d53fdc1e>] __kmalloc_track_caller+0x15d/0x2c0 mm/slab.c:3675
    [<00000000c742d29c>] kstrdup+0x3a/0x70 mm/util.c:52
    [<00000000d3df5d2b>] kstrdup_const+0x48/0x60 mm/util.c:74
    [<00000000d75a8fa8>] kvasprintf_const+0x7e/0xe0 lib/kasprintf.c:48
    [<00000000ebee37a0>] kobject_set_name_vargs+0x40/0xe0 lib/kobject.c:289
    [<00000000c23c056a>] dev_set_name+0x63/0x90 drivers/base/core.c:1915
    [<000000004c47b6d3>] netdev_register_kobject+0x5a/0x1b0  
net/core/net-sysfs.c:1727
    [<000000005fb074af>] register_netdevice+0x397/0x600 net/core/dev.c:8733
    [<00000000bdcf4ebd>] register_netdev+0x24/0x40 net/core/dev.c:8851
    [<0000000042e6c0c4>] br_add_bridge+0x5e/0xa0 net/bridge/br_if.c:456
    [<0000000036402409>] br_ioctl_deviceless_stub+0x30c/0x350  
net/bridge/br_ioctl.c:374
    [<00000000e57c9a76>] sock_ioctl+0x287/0x480 net/socket.c:1141
    [<00000000109b8329>] vfs_ioctl fs/ioctl.c:46 [inline]
    [<00000000109b8329>] file_ioctl fs/ioctl.c:509 [inline]
    [<00000000109b8329>] do_vfs_ioctl+0x62a/0x810 fs/ioctl.c:696
    [<00000000d8eb5a5e>] ksys_ioctl+0x86/0xb0 fs/ioctl.c:713
    [<00000000cd162915>] __do_sys_ioctl fs/ioctl.c:720 [inline]
    [<00000000cd162915>] __se_sys_ioctl fs/ioctl.c:718 [inline]
    [<00000000cd162915>] __x64_sys_ioctl+0x1e/0x30 fs/ioctl.c:718
    [<0000000069b4ac36>] do_syscall_64+0x76/0x1a0  
arch/x86/entry/common.c:301



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