KASAN: use-after-free Read in tipc_named_reinit

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: cb8e59cc Merge git://git.kernel.org/pub/scm/linux/kernel/g..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12eccfd2100000
kernel config: https://syzkaller.appspot.com/x/.config?x=a16ddbc78955e3a9
dashboard link: https://syzkaller.appspot.com/bug?extid=e9cc557752ab126c1b99
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e9cc55...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:252 [inline]
BUG: KASAN: use-after-free in tipc_named_reinit+0x913/0x946 net/tipc/name_distr.c:344
Read of size 8 at addr ffff8880580d2000 by task kworker/1:1/27

CPU: 1 PID: 27 Comm: kworker/1:1 Not tainted 5.7.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events tipc_net_finalize_work
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x188/0x20d lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xd3/0x413 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
__read_once_size include/linux/compiler.h:252 [inline]
tipc_named_reinit+0x913/0x946 net/tipc/name_distr.c:344
tipc_net_finalize net/tipc/net.c:138 [inline]
tipc_net_finalize+0x1cf/0x310 net/tipc/net.c:131
tipc_net_finalize_work+0x55/0x80 net/tipc/net.c:150
process_one_work+0x965/0x16a0 kernel/workqueue.c:2268
worker_thread+0x96/0xe20 kernel/workqueue.c:2414
kthread+0x388/0x470 kernel/kthread.c:268
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351

Allocated by task 22186:
save_stack+0x1b/0x40 mm/kasan/common.c:48
set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc mm/kasan/common.c:494 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:467
kmem_cache_alloc_trace+0x153/0x7d0 mm/slab.c:3551
kmalloc include/linux/slab.h:555 [inline]
kzalloc include/linux/slab.h:669 [inline]
tipc_nametbl_init+0x1b5/0x490 net/tipc/name_table.c:852
tipc_init_net+0x381/0x5c0 net/tipc/core.c:79
ops_init+0xaf/0x420 net/core/net_namespace.c:151
setup_net+0x2de/0x860 net/core/net_namespace.c:341
copy_net_ns+0x293/0x590 net/core/net_namespace.c:482
create_new_namespaces+0x3fb/0xb30 kernel/nsproxy.c:110
unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:231
ksys_unshare+0x43d/0x8e0 kernel/fork.c:2984
__do_sys_unshare kernel/fork.c:3052 [inline]
__se_sys_unshare kernel/fork.c:3050 [inline]
__x64_sys_unshare+0x2d/0x40 kernel/fork.c:3050
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 191:
save_stack+0x1b/0x40 mm/kasan/common.c:48
set_track mm/kasan/common.c:56 [inline]
kasan_set_free_info mm/kasan/common.c:316 [inline]
__kasan_slab_free+0xf7/0x140 mm/kasan/common.c:455
__cache_free mm/slab.c:3426 [inline]
kfree+0x109/0x2b0 mm/slab.c:3757
tipc_exit_net+0x2c/0x270 net/tipc/core.c:113
ops_exit_list.isra.0+0xa8/0x150 net/core/net_namespace.c:186
cleanup_net+0x511/0xa50 net/core/net_namespace.c:603
process_one_work+0x965/0x16a0 kernel/workqueue.c:2268
worker_thread+0x96/0xe20 kernel/workqueue.c:2414
kthread+0x388/0x470 kernel/kthread.c:268
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351

The buggy address belongs to the object at ffff8880580d0000
which belongs to the cache kmalloc-16k of size 16384
The buggy address is located 8192 bytes inside of
16384-byte region [ffff8880580d0000, ffff8880580d4000)
The buggy address belongs to the page:
page:ffffea0001603400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea0001603400 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea0001509008 ffff8880aa001c50 ffff8880aa002380
raw: 0000000000000000 ffff8880580d0000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880580d1f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880580d1f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880580d2000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880580d2080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880580d2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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