KASAN: use-after-free Read in kernfs_add_one (2)

Status: auto-obsoleted due to no activity on 2025/12/19 02:39
Reported-by: syzbot+50be1c823c917382ca04@syzkaller.appspotmail.com
First crash: 395d, last: 320d
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Read in kernfs_add_one kernfs 19 C error inconclusive 39 838d 1768d 0/29 auto-obsoleted due to no activity on 2024/08/14 07:44
linux-6.1 KASAN: use-after-free Read in kernfs_add_one (2) 19 1 828d 828d 0/3 auto-obsoleted due to no activity on 2024/07/29 04:04
linux-6.1 KASAN: use-after-free Read in kernfs_add_one (3) 19 1 720d 720d 0/3 auto-obsoleted due to no activity on 2024/11/13 12:08
linux-6.1 KASAN: use-after-free Read in kernfs_add_one (4) origin:upstream missing-backport 19 C inconclusive 5 355d 581d 0/3 upstream: reported C repro on 2024/12/22 11:05
linux-6.1 KASAN: use-after-free Read in kernfs_add_one 19 1 1135d 1135d 0/3 auto-obsoleted due to no activity on 2023/09/26 01:13
linux-5.15 KASAN: use-after-free Read in kernfs_add_one 19 1 1031d 1031d 0/3 auto-obsoleted due to no activity on 2024/01/09 18:18
upstream KASAN: slab-use-after-free Read in kernfs_add_one kernfs 19 6 506d 667d 0/29 auto-obsoleted due to no activity on 2025/06/15 10:44

Sample crash report:
usb 5-1: Direct firmware load for ueagle-atm/eagleII.fw failed with error -2
usb 5-1: Falling back to sysfs fallback for: ueagle-atm/eagleII.fw
==================================================================
BUG: KASAN: use-after-free in kernfs_root fs/kernfs/kernfs-internal.h:48 [inline]
BUG: KASAN: use-after-free in kernfs_add_one+0x4e6/0x6c0 fs/kernfs/dir.c:787
Read of size 8 at addr ffff8880614e22e8 by task kworker/0:16/4497

CPU: 0 PID: 4497 Comm: kworker/0:16 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: events request_firmware_work_func
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 kernfs_root fs/kernfs/kernfs-internal.h:48 [inline]
 kernfs_add_one+0x4e6/0x6c0 fs/kernfs/dir.c:787
 kernfs_create_dir_ns+0xda/0x120 fs/kernfs/dir.c:1015
 sysfs_create_dir_ns+0x120/0x280 fs/sysfs/dir.c:59
 create_dir lib/kobject.c:89 [inline]
 kobject_add_internal+0x662/0xd00 lib/kobject.c:263
 kobject_add_varg lib/kobject.c:398 [inline]
 kobject_add+0x152/0x210 lib/kobject.c:450
 class_dir_create_and_add drivers/base/core.c:2966 [inline]
 get_device_parent+0x380/0x3f0 drivers/base/core.c:3021
 device_add+0x335/0xfb0 drivers/base/core.c:3333
 fw_load_sysfs_fallback drivers/base/firmware_loader/fallback.c:507 [inline]
 fw_load_from_user_helper drivers/base/firmware_loader/fallback.c:583 [inline]
 firmware_fallback_sysfs+0x3e9/0xbc0 drivers/base/firmware_loader/fallback.c:659
 _request_firmware+0xc86/0x12b0 drivers/base/firmware_loader/main.c:876
 request_firmware_work_func+0xac/0x1b0 drivers/base/firmware_loader/main.c:1127
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Allocated by task 4497:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 __kasan_slab_alloc+0x9c/0xd0 mm/kasan/common.c:467
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x100/0x290 mm/slub.c:3238
 kmem_cache_zalloc include/linux/slab.h:725 [inline]
 __kernfs_new_node+0xd6/0x680 fs/kernfs/dir.c:593
 kernfs_new_node+0x148/0x250 fs/kernfs/dir.c:669
 kernfs_create_dir_ns+0x40/0x120 fs/kernfs/dir.c:1005
 sysfs_create_dir_ns+0x120/0x280 fs/sysfs/dir.c:59
 create_dir lib/kobject.c:89 [inline]
 kobject_add_internal+0x662/0xd00 lib/kobject.c:263
 kobject_add_varg lib/kobject.c:398 [inline]
 kobject_add+0x152/0x210 lib/kobject.c:450
 class_dir_create_and_add drivers/base/core.c:2966 [inline]
 get_device_parent+0x380/0x3f0 drivers/base/core.c:3021
 device_add+0x335/0xfb0 drivers/base/core.c:3333
 fw_load_sysfs_fallback drivers/base/firmware_loader/fallback.c:507 [inline]
 fw_load_from_user_helper drivers/base/firmware_loader/fallback.c:583 [inline]
 firmware_fallback_sysfs+0x3e9/0xbc0 drivers/base/firmware_loader/fallback.c:659
 _request_firmware+0xc86/0x12b0 drivers/base/firmware_loader/main.c:876
 request_firmware_work_func+0xac/0x1b0 drivers/base/firmware_loader/main.c:1127
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

Freed by task 4232:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kmem_cache_free+0x8f/0x210 mm/slub.c:3520
 kernfs_put+0x319/0x490 fs/kernfs/dir.c:547
 __kernfs_remove+0x9aa/0xc50 fs/kernfs/dir.c:1393
 kernfs_remove+0x1d/0x30 fs/kernfs/dir.c:1406
 __kobject_del+0xe1/0x2f0 lib/kobject.c:628
 kobject_del+0x41/0x60 lib/kobject.c:651
 device_del+0x8f8/0xa70 drivers/base/core.c:3612
 usb_disconnect+0x573/0x8a0 drivers/usb/core/hub.c:2313
 hub_port_connect drivers/usb/core/hub.c:5341 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5637 [inline]
 port_event drivers/usb/core/hub.c:5799 [inline]
 hub_event+0x1e9f/0x5560 drivers/usb/core/hub.c:5881
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

The buggy address belongs to the object at ffff8880614e22b8
 which belongs to the cache kernfs_node_cache of size 168
The buggy address is located 48 bytes inside of
 168-byte region [ffff8880614e22b8, ffff8880614e2360)
The buggy address belongs to the page:
page:ffffea0001853880 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x614e2
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea0000882dc0 000000140000000b ffff8880169e9b40
raw: 0000000000000000 0000000080110011 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 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 4185, ts 70292989657, free_ts 25767580333
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x1b77/0x1c60 mm/page_alloc.c:4192
 __alloc_pages+0x1e1/0x470 mm/page_alloc.c:5487
 alloc_slab_page mm/slub.c:1780 [inline]
 allocate_slab mm/slub.c:1917 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1980
 ___slab_alloc+0x81e/0xdf0 mm/slub.c:3013
 __slab_alloc mm/slub.c:3100 [inline]
 slab_alloc_node mm/slub.c:3191 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x195/0x290 mm/slub.c:3238
 kmem_cache_zalloc include/linux/slab.h:725 [inline]
 __kernfs_new_node+0xd6/0x680 fs/kernfs/dir.c:593
 kernfs_new_node+0x148/0x250 fs/kernfs/dir.c:669
 kernfs_create_dir_ns+0x40/0x120 fs/kernfs/dir.c:1005
 sysfs_create_dir_ns+0x120/0x280 fs/sysfs/dir.c:59
 create_dir lib/kobject.c:89 [inline]
 kobject_add_internal+0x662/0xd00 lib/kobject.c:263
 kobject_add_varg lib/kobject.c:398 [inline]
 kobject_init_and_add+0x122/0x190 lib/kobject.c:481
 netdev_queue_add_kobject net/core/net-sysfs.c:1666 [inline]
 netdev_queue_update_kobjects+0x19c/0x3e0 net/core/net-sysfs.c:1711
 register_queue_kobjects net/core/net-sysfs.c:1772 [inline]
 netdev_register_kobject+0x265/0x310 net/core/net-sysfs.c:2018
 register_netdevice+0x1019/0x16b0 net/core/dev.c:10397
 xfrmi_create net/xfrm/xfrm_interface_core.c:156 [inline]
 xfrmi_newlink+0x336/0x4c0 net/xfrm/xfrm_interface_core.c:706
 __rtnl_newlink net/core/rtnetlink.c:3524 [inline]
 rtnl_newlink+0x114c/0x17d0 net/core/rtnetlink.c:3572
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x94/0x280 mm/page_alloc.c:3396
 free_contig_range+0x96/0xf0 mm/page_alloc.c:9406
 destroy_args+0x100/0xa20 mm/debug_vm_pgtable.c:1018
 debug_vm_pgtable+0x318/0x370 mm/debug_vm_pgtable.c:1336
 do_one_initcall+0x1ee/0x680 init/main.c:1302
 do_initcall_level+0x137/0x1f0 init/main.c:1375
 do_initcalls+0x4b/0x90 init/main.c:1391
 kernel_init_freeable+0x3ce/0x560 init/main.c:1615
 kernel_init+0x19/0x1b0 init/main.c:1506
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

Memory state around the buggy address:
 ffff8880614e2180: fb fb fc fc fc fc fc fc fc fc fa fb fb fb fb fb
 ffff8880614e2200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc
>ffff8880614e2280: fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb fb
                                                          ^
 ffff8880614e2300: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff8880614e2380: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/10 02:39 linux-5.15.y de9476bb4f1b fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in kernfs_add_one
2025/06/26 17:31 linux-5.15.y 1c700860e8bc 803ce19b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in kernfs_add_one
* Struck through repros no longer work on HEAD.