KASAN: vmalloc-out-of-bounds Read in csd_lock_record

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 9e50b94b Add linux-next specific files for 20200703
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1610fc47100000
kernel config: https://syzkaller.appspot.com/x/.config?x=f99cc0faa1476ed6
dashboard link: https://syzkaller.appspot.com/bug?extid=69e2e241def6df9b3071
compiler: gcc (GCC) 10.1.0-syz 20200507
CC: [big...@linutronix.de linux-...@vger.kernel.org mi...@kernel.org pau...@kernel.org pet...@infradead.org tg...@linutronix.de]

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+69e2e2...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: vmalloc-out-of-bounds in csd_lock_record+0xcb/0xe0 kernel/smp.c:118
Read of size 8 at addr ffffc90004b477f0 by task kworker/u4:7/12390

CPU: 1 PID: 12390 Comm: kworker/u4:7 Not tainted 5.8.0-rc3-next-20200703-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x18f/0x20d lib/dump_stack.c:118
print_address_description.constprop.0.cold+0x5/0x436 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
csd_lock_record+0xcb/0xe0 kernel/smp.c:118
flush_smp_call_function_queue+0x285/0x730 kernel/smp.c:391
__sysvec_call_function_single+0x98/0x490 arch/x86/kernel/smp.c:248
asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706
</IRQ>
__run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
sysvec_call_function_single+0xe0/0x120 arch/x86/kernel/smp.c:243
asm_sysvec_call_function_single+0x12/0x20 arch/x86/include/asm/idtentry.h:604
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:765 [inline]
RIP: 0010:lock_acquire+0x270/0xad0 kernel/locking/lockdep.c:4962
Code: 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 0f 85 f8 06 00 00 48 83 3d 6d c1 5a 08 00 0f 84 a6 05 00 00 48 8b 7c 24 08 57 9d <0f> 1f 44 00 00 48 b8 00 00 00 00 00 fc ff df 48 03 44 24 10 48 c7
RSP: 0018:ffffc90001817a38 EFLAGS: 00000282
RAX: 1ffffffff1369fe0 RBX: ffff88804cb3c540 RCX: 0000000000000001
RDX: dffffc0000000000 RSI: 6c175b7e6c583a8b RDI: 0000000000000282
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8c5a7a27
R10: fffffbfff18b4f44 R11: 0000000000000000 R12: 0000000000000002
R13: ffffffff89bc3040 R14: 0000000000000000 R15: ffff88804cb3c540
rcu_lock_acquire include/linux/rcupdate.h:241 [inline]
rcu_read_lock include/linux/rcupdate.h:634 [inline]
inet_twsk_purge+0x112/0x7b0 net/ipv4/inet_timewait_sock.c:268
ops_exit_list+0x10d/0x160 net/core/net_namespace.c:189
cleanup_net+0x4ea/0xa00 net/core/net_namespace.c:603
process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
kthread+0x3b5/0x4a0 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294


Memory state around the buggy address:
ffffc90004b47680: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
ffffc90004b47700: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
>ffffc90004b47780: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
^
ffffc90004b47800: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
ffffc90004b47880: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
==================================================================


---
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[Dmitry Vyukov]

#syz dup: KASAN: out-of-bounds Read in csd_lock_record

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[Dmitry Vyukov]

I think this is the same as:

#syz dup: KASAN: stack-out-of-bounds Read in csd_lock_record