[syzbot] [net?] memory leak in mld_newpack (2)

[syzbot <syzbot+6667f589ca803e522dd5@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    1c7873e33645 mm: lock newly mapped VMA with corrected orde..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=154d4628a80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=832b404e095b70c0
dashboard link: https://syzkaller.appspot.com/bug?extid=6667f589ca803e522dd5
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=15571688a80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/43b42bd2cf70/disk-1c7873e3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/011ba1b9e8c1/vmlinux-1c7873e3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/18b349342595/bzImage-1c7873e3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6667f589ca803e522dd5@syzkaller.appspotmail.com

BUG: memory leak
unreferenced object 0xffff88811bcfc000 (size 2048):
  comm "kworker/0:2", pid 2509, jiffies 4295029694 (age 93.370s)
  hex dump (first 32 bytes):
    00 00 33 33 00 00 00 16 fa 19 b9 c5 55 d7 86 dd  ..33........U...
    60 00 00 00 00 24 00 01 00 00 00 00 00 00 00 00  `....$..........
  backtrace:
    [<ffffffff8154c38b>] __do_kmalloc_node mm/slab_common.c:984 [inline]
    [<ffffffff8154c38b>] __kmalloc_node_track_caller+0x4b/0x120 mm/slab_common.c:1005
    [<ffffffff83e184ec>] kmalloc_reserve+0x9c/0x180 net/core/skbuff.c:575
    [<ffffffff83e1bb55>] __alloc_skb+0xd5/0x230 net/core/skbuff.c:644
    [<ffffffff83e24b6f>] alloc_skb include/linux/skbuff.h:1289 [inline]
    [<ffffffff83e24b6f>] alloc_skb_with_frags+0x6f/0x340 net/core/skbuff.c:6228
    [<ffffffff83e116b3>] sock_alloc_send_pskb+0x3a3/0x3e0 net/core/sock.c:2782
    [<ffffffff842fc401>] sock_alloc_send_skb include/net/sock.h:1871 [inline]
    [<ffffffff842fc401>] mld_newpack.isra.0+0x81/0x220 net/ipv6/mcast.c:1748
    [<ffffffff842fc66c>] add_grhead+0xcc/0xf0 net/ipv6/mcast.c:1851
    [<ffffffff842fce63>] add_grec+0x7d3/0x840 net/ipv6/mcast.c:1989
    [<ffffffff842ff31f>] mld_send_cr net/ipv6/mcast.c:2115 [inline]
    [<ffffffff842ff31f>] mld_ifc_work+0x26f/0x750 net/ipv6/mcast.c:2653
    [<ffffffff812b19e4>] process_one_work+0x2c4/0x620 kernel/workqueue.c:2597
    [<ffffffff812b233d>] worker_thread+0x5d/0x5c0 kernel/workqueue.c:2748
    [<ffffffff812bbde3>] kthread+0x133/0x180 kernel/kthread.c:389
    [<ffffffff81002b5f>] ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

BUG: memory leak
unreferenced object 0xffff88811bcfd800 (size 2048):
  comm "kworker/0:4", pid 5090, jiffies 4295029925 (age 91.060s)
  hex dump (first 32 bytes):
    00 00 33 33 00 00 00 16 aa aa aa aa aa 1b 86 dd  ..33............
    60 00 00 00 00 38 00 01 00 00 00 00 00 00 00 00  `....8..........
  backtrace:
    [<ffffffff8154c38b>] __do_kmalloc_node mm/slab_common.c:984 [inline]
    [<ffffffff8154c38b>] __kmalloc_node_track_caller+0x4b/0x120 mm/slab_common.c:1005
    [<ffffffff83e184ec>] kmalloc_reserve+0x9c/0x180 net/core/skbuff.c:575
    [<ffffffff83e1bb55>] __alloc_skb+0xd5/0x230 net/core/skbuff.c:644
    [<ffffffff83e24b6f>] alloc_skb include/linux/skbuff.h:1289 [inline]
    [<ffffffff83e24b6f>] alloc_skb_with_frags+0x6f/0x340 net/core/skbuff.c:6228
    [<ffffffff83e116b3>] sock_alloc_send_pskb+0x3a3/0x3e0 net/core/sock.c:2782
    [<ffffffff842fc401>] sock_alloc_send_skb include/net/sock.h:1871 [inline]
    [<ffffffff842fc401>] mld_newpack.isra.0+0x81/0x220 net/ipv6/mcast.c:1748
    [<ffffffff842fc66c>] add_grhead+0xcc/0xf0 net/ipv6/mcast.c:1851
    [<ffffffff842fce63>] add_grec+0x7d3/0x840 net/ipv6/mcast.c:1989
    [<ffffffff842ff31f>] mld_send_cr net/ipv6/mcast.c:2115 [inline]
    [<ffffffff842ff31f>] mld_ifc_work+0x26f/0x750 net/ipv6/mcast.c:2653
    [<ffffffff812b19e4>] process_one_work+0x2c4/0x620 kernel/workqueue.c:2597
    [<ffffffff812b233d>] worker_thread+0x5d/0x5c0 kernel/workqueue.c:2748
    [<ffffffff812bbde3>] kthread+0x133/0x180 kernel/kthread.c:389
    [<ffffffff81002b5f>] ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308



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