[syzbot] [kernfs?] KASAN: slab-use-after-free Read in kernfs_get

syzbot
2024-02-16T10:15:17Z

Hello,

syzbot found the following issue on:

HEAD commit: 4f5e5092fdbf Merge tag 'net-6.8-rc5' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14c58494180000
kernel config: https://syzkaller.appspot.com/x/.config?x=1d7c92dd8d5c7a1e
dashboard link: https://syzkaller.appspot.com/bug?extid=615e0ade319f27aeab87
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d430539932db/disk-4f5e5092.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6369586e33b7/vmlinux-4f5e5092.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9c1e38f80254/bzImage-4f5e5092.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+615e0ade319f27aeab87@syzkaller.appspotmail.com

usb 4-1: Direct firmware load for ueagle-atm/adi930.fw failed with error -2
usb 4-1: Falling back to sysfs fallback for: ueagle-atm/adi930.fw
==================================================================
BUG: KASAN: slab-use-after-free in instrument_atomic_read include/linux/instrumented.h:68 [inline]
BUG: KASAN: slab-use-after-free in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
BUG: KASAN: slab-use-after-free in kernfs_get+0x20/0x90 fs/kernfs/dir.c:526
Read of size 4 at addr ffff888029e1f3e0 by task kworker/0:0/8

CPU: 0 PID: 8 Comm: kworker/0:0 Not tainted 6.8.0-rc4-syzkaller-00180-g4f5e5092fdbf #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
Workqueue: events request_firmware_work_func
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:377 [inline]
print_report+0x167/0x540 mm/kasan/report.c:488
kasan_report+0x142/0x180 mm/kasan/report.c:601
kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
instrument_atomic_read include/linux/instrumented.h:68 [inline]
atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
kernfs_get+0x20/0x90 fs/kernfs/dir.c:526
sysfs_get include/linux/sysfs.h:653 [inline]
create_dir lib/kobject.c:87 [inline]
kobject_add_internal+0x483/0x8a0 lib/kobject.c:238
kobject_add_varg lib/kobject.c:372 [inline]
kobject_add+0x152/0x220 lib/kobject.c:424
device_add+0x4b5/0xca0 drivers/base/core.c:3563
fw_load_sysfs_fallback drivers/base/firmware_loader/fallback.c:86 [inline]
fw_load_from_user_helper drivers/base/firmware_loader/fallback.c:162 [inline]
firmware_fallback_sysfs+0x307/0x9e0 drivers/base/firmware_loader/fallback.c:238
_request_firmware+0xc97/0x1250 drivers/base/firmware_loader/main.c:910
request_firmware_work_func+0x12a/0x280 drivers/base/firmware_loader/main.c:1161
process_one_work kernel/workqueue.c:2633 [inline]
process_scheduled_works+0x913/0x1420 kernel/workqueue.c:2706
worker_thread+0xa5f/0x1000 kernel/workqueue.c:2787
kthread+0x2ef/0x390 kernel/kthread.c:388
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242
</TASK>

Allocated by task 8:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
unpoison_slab_object mm/kasan/common.c:314 [inline]
__kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:340
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook mm/slub.c:3813 [inline]
slab_alloc_node mm/slub.c:3860 [inline]
kmem_cache_alloc+0x16f/0x340 mm/slub.c:3867
kmem_cache_zalloc include/linux/slab.h:701 [inline]
__kernfs_new_node+0xd8/0x880 fs/kernfs/dir.c:615
kernfs_new_node+0x13a/0x240 fs/kernfs/dir.c:691
kernfs_create_dir_ns+0x43/0x120 fs/kernfs/dir.c:1052
sysfs_create_dir_ns+0x189/0x3a0 fs/sysfs/dir.c:59
create_dir lib/kobject.c:73 [inline]
kobject_add_internal+0x40d/0x8a0 lib/kobject.c:238
kobject_add_varg lib/kobject.c:372 [inline]
kobject_add+0x152/0x220 lib/kobject.c:424
device_add+0x4b5/0xca0 drivers/base/core.c:3563
fw_load_sysfs_fallback drivers/base/firmware_loader/fallback.c:86 [inline]
fw_load_from_user_helper drivers/base/firmware_loader/fallback.c:162 [inline]
firmware_fallback_sysfs+0x307/0x9e0 drivers/base/firmware_loader/fallback.c:238
_request_firmware+0xc97/0x1250 drivers/base/firmware_loader/main.c:910
request_firmware_work_func+0x12a/0x280 drivers/base/firmware_loader/main.c:1161
process_one_work kernel/workqueue.c:2633 [inline]
process_scheduled_works+0x913/0x1420 kernel/workqueue.c:2706
worker_thread+0xa5f/0x1000 kernel/workqueue.c:2787
kthread+0x2ef/0x390 kernel/kthread.c:388
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242

Freed by task 9:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x4e/0x60 mm/kasan/generic.c:640
poison_slab_object+0xa6/0xe0 mm/kasan/common.c:241
__kasan_slab_free+0x34/0x70 mm/kasan/common.c:257
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2121 [inline]
slab_free mm/slub.c:4299 [inline]
kmem_cache_free+0x102/0x2a0 mm/slub.c:4363
kernfs_put+0x2a4/0x420 fs/kernfs/dir.c:569
__kernfs_remove+0x76e/0x880 fs/kernfs/dir.c:1499
kernfs_remove+0x7a/0xa0 fs/kernfs/dir.c:1519
__kobject_del+0xd1/0x300 lib/kobject.c:601
kobject_del+0x45/0x60 lib/kobject.c:624
device_del+0x83d/0xa30 drivers/base/core.c:3834
usb_disconnect+0x60b/0x950 drivers/usb/core/hub.c:2295
hub_port_connect drivers/usb/core/hub.c:5323 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5623 [inline]
port_event drivers/usb/core/hub.c:5783 [inline]
hub_event+0x1e62/0x50f0 drivers/usb/core/hub.c:5865
process_one_work kernel/workqueue.c:2633 [inline]
process_scheduled_works+0x913/0x1420 kernel/workqueue.c:2706
worker_thread+0xa5f/0x1000 kernel/workqueue.c:2787
kthread+0x2ef/0x390 kernel/kthread.c:388
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242

The buggy address belongs to the object at ffff888029e1f3e0
which belongs to the cache kernfs_node_cache of size 168
The buggy address is located 0 bytes inside of
freed 168-byte region [ffff888029e1f3e0, ffff888029e1f488)

The buggy address belongs to the physical page:
page:ffffea0000a787c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x29e1f
flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000800 ffff8880162b4dc0 ffffea0001d9c7c0 0000000000000004
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 20250, tgid 20246 (syz-executor.1), ts 407489926347, free_ts 399703976306
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1533
prep_new_page mm/page_alloc.c:1540 [inline]
get_page_from_freelist+0x33ea/0x3580 mm/page_alloc.c:3311
__alloc_pages+0x255/0x680 mm/page_alloc.c:4567
__alloc_pages_node include/linux/gfp.h:238 [inline]
alloc_pages_node include/linux/gfp.h:261 [inline]
alloc_slab_page+0x5f/0x160 mm/slub.c:2190
allocate_slab mm/slub.c:2354 [inline]
new_slab+0x84/0x2f0 mm/slub.c:2407
___slab_alloc+0xd17/0x13e0 mm/slub.c:3540
__slab_alloc mm/slub.c:3625 [inline]
__slab_alloc_node mm/slub.c:3678 [inline]
slab_alloc_node mm/slub.c:3850 [inline]
kmem_cache_alloc+0x24d/0x340 mm/slub.c:3867
kmem_cache_zalloc include/linux/slab.h:701 [inline]
__kernfs_new_node+0xd8/0x880 fs/kernfs/dir.c:615
kernfs_new_node+0x13a/0x240 fs/kernfs/dir.c:691
__kernfs_create_file+0x49/0x2f0 fs/kernfs/file.c:1025
sysfs_add_file_mode_ns+0x24a/0x310 fs/sysfs/file.c:307
create_files fs/sysfs/group.c:64 [inline]
internal_create_group+0x4f4/0xf20 fs/sysfs/group.c:152
internal_create_groups fs/sysfs/group.c:192 [inline]
sysfs_create_groups+0x56/0x120 fs/sysfs/group.c:218
device_add_groups drivers/base/core.c:2727 [inline]
device_add_attrs+0x199/0x600 drivers/base/core.c:2847
device_add+0x57d/0xca0 drivers/base/core.c:3579
netdev_register_kobject+0x17e/0x310 net/core/net-sysfs.c:2055
page last free pid 55 tgid 55 stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1140 [inline]
free_unref_page_prepare+0x968/0xa90 mm/page_alloc.c:2346
free_unref_page+0x37/0x3f0 mm/page_alloc.c:2486
kasan_depopulate_vmalloc_pte+0x74/0x90 mm/kasan/shadow.c:415
apply_to_pte_range mm/memory.c:2619 [inline]
apply_to_pmd_range mm/memory.c:2663 [inline]
apply_to_pud_range mm/memory.c:2699 [inline]
apply_to_p4d_range mm/memory.c:2735 [inline]
__apply_to_page_range+0x8ec/0xe40 mm/memory.c:2769
kasan_release_vmalloc+0x9a/0xb0 mm/kasan/shadow.c:532
__purge_vmap_area_lazy+0x163f/0x1a10 mm/vmalloc.c:1770
drain_vmap_area_work+0x40/0xd0 mm/vmalloc.c:1804
process_one_work kernel/workqueue.c:2633 [inline]
process_scheduled_works+0x913/0x1420 kernel/workqueue.c:2706
worker_thread+0xa5f/0x1000 kernel/workqueue.c:2787
kthread+0x2ef/0x390 kernel/kthread.c:388
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242

Memory state around the buggy address:
ffff888029e1f280: fb fb fb fc fc fc fc fc fc fc fc fc fc fb fb fb
ffff888029e1f300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888029e1f380: fb fb fc fc fc fc fc fc fc fc fc fc fa fb fb fb
^
ffff888029e1f400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888029e1f480: fb fc fc fc fc fc fc fc fc fc fc 00 00 00 00 00
==================================================================

---
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 syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup