memory leak in xskq_create

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    a68a0262 mm/madvise: remove racy mm ownership check
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=165b9413500000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4305fa9ea70c7a9f
dashboard link: https://syzkaller.appspot.com/bug?extid=cfa88ddd0655afa88763
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1180a237500000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=114067cf500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cfa88ddd0655afa88763@xxxxxxxxxxxxxxxxxxxxxxxxx

Debian GNU/Linux 9 syzkaller ttyS0
Warning: Permanently added '10.128.0.50' (ECDSA) to the list of known hosts.
executing program
executing program
BUG: memory leak
unreferenced object 0xffff88810f897940 (size 64):
  comm "syz-executor991", pid 8502, jiffies 4294942194 (age 14.080s)
  hex dump (first 32 bytes):
    7f 00 00 00 80 00 00 00 00 00 00 00 00 00 00 00  ................
    00 a0 37 0c 81 88 ff ff 00 00 00 00 00 00 00 00  ..7.............
  backtrace:
    [<00000000639d0dd1>] xskq_create+0x23/0xd0 include/linux/slab.h:552
    [<00000000b680b035>] xsk_init_queue net/xdp/xsk.c:508 [inline]
    [<00000000b680b035>] xsk_setsockopt+0x1c4/0x590 net/xdp/xsk.c:875
    [<000000002b302260>] __sys_setsockopt+0x1b0/0x360 net/socket.c:2132
    [<00000000ae03723e>] __do_sys_setsockopt net/socket.c:2143 [inline]
    [<00000000ae03723e>] __se_sys_setsockopt net/socket.c:2140 [inline]
    [<00000000ae03723e>] __x64_sys_setsockopt+0x22/0x30 net/socket.c:2140
    [<0000000005c2b4a0>] do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
    [<0000000003db140f>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

BUG: memory leak
unreferenced object 0xffff88810f8979c0 (size 64):
  comm "syz-executor991", pid 8503, jiffies 4294942194 (age 14.080s)
  hex dump (first 32 bytes):
    ff 03 00 00 00 04 00 00 00 00 00 00 00 00 00 00  ................
    00 00 13 12 81 88 ff ff 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000639d0dd1>] xskq_create+0x23/0xd0 include/linux/slab.h:552
    [<00000000b680b035>] xsk_init_queue net/xdp/xsk.c:508 [inline]
    [<00000000b680b035>] xsk_setsockopt+0x1c4/0x590 net/xdp/xsk.c:875
    [<000000002b302260>] __sys_setsockopt+0x1b0/0x360 net/socket.c:2132
    [<00000000ae03723e>] __do_sys_setsockopt net/socket.c:2143 [inline]
    [<00000000ae03723e>] __se_sys_setsockopt net/socket.c:2140 [inline]
    [<00000000ae03723e>] __x64_sys_setsockopt+0x22/0x30 net/socket.c:2140
    [<0000000005c2b4a0>] do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
    [<0000000003db140f>] entry_SYSCALL_64_after_hwframe+0x44/0xa9



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