Re: [syzbot] [pm?] KASAN: use-after-free Read in netdev_unregister_kobject

[syzbot <syzbot+6cf5652d3df49fae2e3f@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in netdev_unregister_kobject

==================================================================
BUG: KASAN: use-after-free in device_for_each_child+0xa7/0x170 drivers/base/core.c:4044
Read of size 8 at addr ffff8880293555f8 by task kbnepd bnep0/5664

CPU: 0 PID: 5664 Comm: kbnepd bnep0 Not tainted 6.9.0-rc4-syzkaller-00173-g3cdb45594619-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 device_for_each_child+0xa7/0x170 drivers/base/core.c:4044
 pm_runtime_set_memalloc_noio+0x114/0x260 drivers/base/power/runtime.c:248
 netdev_unregister_kobject+0x178/0x250 net/core/net-sysfs.c:2106
 unregister_netdevice_many_notify+0x11dd/0x16e0 net/core/dev.c:11135
 unregister_netdevice_many net/core/dev.c:11163 [inline]
 unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11042
 unregister_netdevice include/linux/netdevice.h:3115 [inline]
 unregister_netdev+0x1c/0x30 net/core/dev.c:11181
 bnep_session+0x2e09/0x3000 net/bluetooth/bnep/core.c:525
 kthread+0x2f2/0x390 kernel/kthread.c:388
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x29355
flags: 0xfff80000000000(node=0|zone=1|lastcpupid=0xfff)
page_type: 0xffffffff()
raw: 00fff80000000000 ffffea0000a4d588 ffffea0000a4d508 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x140dc0(GFP_USER|__GFP_COMP|__GFP_ZERO), pid 5470, tgid 1627921193 (syz-executor.4), ts 5470, free_ts 128431373442
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1534
 prep_new_page mm/page_alloc.c:1541 [inline]
 get_page_from_freelist+0x3410/0x35b0 mm/page_alloc.c:3317
 __alloc_pages+0x256/0x6c0 mm/page_alloc.c:4575
 __alloc_pages_node include/linux/gfp.h:238 [inline]
 alloc_pages_node include/linux/gfp.h:261 [inline]
 __kmalloc_large_node+0x91/0x1f0 mm/slub.c:3911
 __do_kmalloc_node mm/slub.c:3954 [inline]
 __kmalloc+0x320/0x4a0 mm/slub.c:3979
 kmalloc include/linux/slab.h:632 [inline]
 kzalloc include/linux/slab.h:749 [inline]
 hci_alloc_dev_priv+0x27/0x2030 net/bluetooth/hci_core.c:2500
 hci_alloc_dev include/net/bluetooth/hci_core.h:1672 [inline]
 __vhci_create_device drivers/bluetooth/hci_vhci.c:406 [inline]
 vhci_create_device+0x12e/0x720 drivers/bluetooth/hci_vhci.c:480
 vhci_get_user drivers/bluetooth/hci_vhci.c:537 [inline]
 vhci_write+0x3cb/0x480 drivers/bluetooth/hci_vhci.c:617
 call_write_iter include/linux/fs.h:2110 [inline]
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0xa86/0xcb0 fs/read_write.c:590
 ksys_write+0x1a0/0x2c0 fs/read_write.c:643
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5470 tgid 5470 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1141 [inline]
 free_unref_page_prepare+0x986/0xab0 mm/page_alloc.c:2347
 free_unref_page+0x37/0x3f0 mm/page_alloc.c:2487
 __folio_put_large+0x13f/0x190 mm/swap.c:132
 __folio_put+0x299/0x390 mm/swap.c:140
 folio_put include/linux/mm.h:1506 [inline]
 free_large_kmalloc+0x105/0x1c0 mm/slub.c:4361
 kfree+0x1ca/0x3a0 mm/slub.c:4384
 hci_release_dev+0x1516/0x16a0 net/bluetooth/hci_core.c:2833
 bt_host_release+0x83/0x90 net/bluetooth/hci_sysfs.c:94
 device_release+0x9b/0x1c0
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x231/0x480 lib/kobject.c:737
 vhci_release+0x8b/0xd0 drivers/bluetooth/hci_vhci.c:675
 __fput+0x42b/0x8a0 fs/file_table.c:422
 task_work_run+0x251/0x310 kernel/task_work.c:180
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0xa1b/0x27e0 kernel/exit.c:878
 do_group_exit+0x207/0x2c0 kernel/exit.c:1027
 __do_sys_exit_group kernel/exit.c:1038 [inline]
 __se_sys_exit_group kernel/exit.c:1036 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1036

Memory state around the buggy address:
 ffff888029355480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888029355500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888029355580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff888029355600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888029355680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


Tested on:

commit:         3cdb4559 Merge tag 's390-6.9-4' of git://git.kernel.or..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=10c3d0d3180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d239903bd07761e5
dashboard link: https://syzkaller.appspot.com/bug?extid=6cf5652d3df49fae2e3f
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=105d6b20980000