KASAN: slab-out-of-bounds Write in tun_free_netdev (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 46c5fdec ANDROID: Add Image.lz4 to arm64 GKI outputs
git tree: android12-5.4
console output: https://syzkaller.appspot.com/x/log.txt?x=152b99a1d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=4aca206efd4419e1
dashboard link: https://syzkaller.appspot.com/bug?extid=aa7f2494218a350296b6
compiler: Debian clang version 11.0.1-2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1037d3e9d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+aa7f24...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in __hlist_del include/linux/list.h:764 [inline]
BUG: KASAN: slab-out-of-bounds in detach_timer kernel/time/timer.c:824 [inline]
BUG: KASAN: slab-out-of-bounds in detach_if_pending kernel/time/timer.c:841 [inline]
BUG: KASAN: slab-out-of-bounds in try_to_del_timer_sync+0x2b1/0x460 kernel/time/timer.c:1238
Write of size 8 at addr ffff8881e549f1c8 by task syz-executor.3/415

CPU: 0 PID: 415 Comm: syz-executor.3 Not tainted 5.4.109-syzkaller-00001-g46c5fdececa6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1d8/0x24e lib/dump_stack.c:118
print_address_description+0x9b/0x650 mm/kasan/report.c:384
__kasan_report+0x182/0x260 mm/kasan/report.c:516
kasan_report+0x30/0x60 mm/kasan/common.c:641
__hlist_del include/linux/list.h:764 [inline]
detach_timer kernel/time/timer.c:824 [inline]
detach_if_pending kernel/time/timer.c:841 [inline]
try_to_del_timer_sync+0x2b1/0x460 kernel/time/timer.c:1238
del_timer_sync+0x78/0xe0 kernel/time/timer.c:1377
tun_flow_uninit drivers/net/tun.c:1374 [inline]
tun_free_netdev+0x99/0x3b0 drivers/net/tun.c:2315
netdev_run_todo+0xb31/0xda0 net/core/dev.c:9408
tun_detach drivers/net/tun.c:743 [inline]
tun_chr_close+0xc0/0xd0 drivers/net/tun.c:3469
__fput+0x27d/0x6c0 fs/file_table.c:281
task_work_run+0x186/0x1b0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop arch/x86/entry/common.c:163 [inline]
prepare_exit_to_usermode+0x2b0/0x310 arch/x86/entry/common.c:194
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x41926b
Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44
RSP: 002b:00007ffeb219fdb0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 000000000041926b
RDX: 0000000000570750 RSI: 0000000000000080 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 00000000005704c0
R10: 00007ffeb219fea0 R11: 0000000000000293 R12: 0000000000063db0
R13: 00000000000003e8 R14: 000000000056bf60 R15: 0000000000063d75

Allocated by task 0:
(stack is not available)

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8881e549ef80
which belongs to the cache mm_struct of size 1040
The buggy address is located 584 bytes inside of
1040-byte region [ffff8881e549ef80, ffff8881e549f390)
The buggy address belongs to the page:
page:ffffea0007952700 refcount:1 mapcount:0 mapping:ffff8881f5cf8280 index:0x0 compound_mapcount: 0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5cf8280
raw: 0000000000000000 00000000800d000d 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8881e549f080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8881e549f100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881e549f180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff8881e549f200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8881e549f280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.