memory leak in genl_rcv_msg

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    32ef9553 Merge tag 'fsnotify_for_v5.5-rc1' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10e778eae00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3ceab2bd652d6555
dashboard link: https://syzkaller.appspot.com/bug?extid=21f04f481f449c8db840
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11808adae00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=137058eae00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+21f04f481f449c8db840@xxxxxxxxxxxxxxxxxxxxxxxxx

BUG: memory leak
unreferenced object 0xffff888121379340 (size 32):
  comm "syz-executor138", pid 7118, jiffies 4294943875 (age 7.840s)
  hex dump (first 32 bytes):
    40 e9 11 84 ff ff ff ff d8 0a b4 83 ff ff ff ff  @...............
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<000000005c57b8f8>] kmemleak_alloc_recursive  
include/linux/kmemleak.h:43 [inline]
    [<000000005c57b8f8>] slab_post_alloc_hook mm/slab.h:586 [inline]
    [<000000005c57b8f8>] slab_alloc mm/slab.c:3319 [inline]
    [<000000005c57b8f8>] kmem_cache_alloc_trace+0x145/0x2c0 mm/slab.c:3548
    [<000000005e5d1167>] kmalloc include/linux/slab.h:556 [inline]
    [<000000005e5d1167>] genl_dumpit_info_alloc net/netlink/genetlink.c:463  
[inline]
    [<000000005e5d1167>] genl_family_rcv_msg_dumpit  
net/netlink/genetlink.c:597 [inline]
    [<000000005e5d1167>] genl_family_rcv_msg net/netlink/genetlink.c:714  
[inline]
    [<000000005e5d1167>] genl_rcv_msg+0x385/0x580  
net/netlink/genetlink.c:734
    [<00000000f3f6d30b>] netlink_rcv_skb+0x61/0x170  
net/netlink/af_netlink.c:2477
    [<000000007bebabc8>] genl_rcv+0x29/0x40 net/netlink/genetlink.c:745
    [<0000000013f3b7b9>] netlink_unicast_kernel  
net/netlink/af_netlink.c:1302 [inline]
    [<0000000013f3b7b9>] netlink_unicast+0x223/0x310  
net/netlink/af_netlink.c:1328
    [<00000000bd3e2e68>] netlink_sendmsg+0x29f/0x550  
net/netlink/af_netlink.c:1917
    [<0000000061329f0f>] sock_sendmsg_nosec net/socket.c:638 [inline]
    [<0000000061329f0f>] sock_sendmsg+0x54/0x70 net/socket.c:658
    [<000000006ede6ef7>] ____sys_sendmsg+0x2d0/0x300 net/socket.c:2329
    [<000000008306e582>] ___sys_sendmsg+0x9c/0x100 net/socket.c:2383
    [<00000000194a34f7>] __sys_sendmsg+0x80/0xf0 net/socket.c:2429
    [<00000000a228fcfc>] __do_sys_sendmsg net/socket.c:2438 [inline]
    [<00000000a228fcfc>] __se_sys_sendmsg net/socket.c:2436 [inline]
    [<00000000a228fcfc>] __x64_sys_sendmsg+0x23/0x30 net/socket.c:2436
    [<0000000035c29044>] do_syscall_64+0x73/0x220  
arch/x86/entry/common.c:294
    [<000000005e1aef5b>] entry_SYSCALL_64_after_hwframe+0x44/0xa9



---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches