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+21f04f...@syzkaller.appspotmail.com

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



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