[syzbot] memory leak in nft_chain_parse_hook

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4c612826bec1 Merge tag 'net-6.0-rc3' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13db4765080000
kernel config: https://syzkaller.appspot.com/x/.config?x=b1831d905b683446
dashboard link: https://syzkaller.appspot.com/bug?extid=5fcdbfab6d6744c57418
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1263c283080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=111b6545080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5fcdbf...@syzkaller.appspotmail.com

executing program
executing program
BUG: memory leak
unreferenced object 0xffff88810180b100 (size 96):
comm "syz-executor133", pid 3619, jiffies 4294945714 (age 12.690s)
hex dump (first 32 bytes):
28 64 23 02 81 88 ff ff 28 64 23 02 81 88 ff ff (d#.....(d#.....
90 a8 aa 83 ff ff ff ff 00 00 b5 0f 81 88 ff ff ................
backtrace:
[<ffffffff83a8c59b>] kmalloc include/linux/slab.h:600 [inline]
[<ffffffff83a8c59b>] nft_netdev_hook_alloc+0x3b/0xc0 net/netfilter/nf_tables_api.c:1901
[<ffffffff83a9239a>] nft_chain_parse_netdev net/netfilter/nf_tables_api.c:1998 [inline]
[<ffffffff83a9239a>] nft_chain_parse_hook+0x33a/0x530 net/netfilter/nf_tables_api.c:2073
[<ffffffff83a9b14b>] nf_tables_addchain.constprop.0+0x10b/0x950 net/netfilter/nf_tables_api.c:2218
[<ffffffff83a9c41b>] nf_tables_newchain+0xa8b/0xc60 net/netfilter/nf_tables_api.c:2593
[<ffffffff83a3d6a6>] nfnetlink_rcv_batch+0xa46/0xd20 net/netfilter/nfnetlink.c:517
[<ffffffff83a3db79>] nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:638 [inline]
[<ffffffff83a3db79>] nfnetlink_rcv+0x1f9/0x220 net/netfilter/nfnetlink.c:656
[<ffffffff83a13b17>] netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
[<ffffffff83a13b17>] netlink_unicast+0x397/0x4c0 net/netlink/af_netlink.c:1345
[<ffffffff83a13fd6>] netlink_sendmsg+0x396/0x710 net/netlink/af_netlink.c:1921
[<ffffffff83865ab6>] sock_sendmsg_nosec net/socket.c:714 [inline]
[<ffffffff83865ab6>] sock_sendmsg+0x56/0x80 net/socket.c:734
[<ffffffff8386601c>] ____sys_sendmsg+0x36c/0x390 net/socket.c:2482
[<ffffffff8386a918>] ___sys_sendmsg+0xa8/0x110 net/socket.c:2536
[<ffffffff8386aaa8>] __sys_sendmsg+0x88/0x100 net/socket.c:2565
[<ffffffff845e5955>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
[<ffffffff845e5955>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
[<ffffffff84800087>] entry_SYSCALL_64_after_hwframe+0x63/0xcd



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