KASAN: use-after-free Read in driver_deferred_probe_del

Status: upstream: reported C repro on 2026/07/31 05:09
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+a452dee91a0f1a8db3a0@syzkaller.appspotmail.com
First crash: 77d, last: 57d
Fix bisection: failed (error log)
  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/10/14 linux-6.1.y (ToT) a500ba24937a C [report] WARNING: refcount bug in usb_add_gadget
2026/10/14 upstream (ToT) 0fcb05b72344 C Didn't crash
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-12 KASAN: slab-use-after-free Read in driver_deferred_probe_del origin:upstream 19 syz, C 4 48d 84d 0/1 premoderation: reported C repro on 2026/07/24 19:07

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in list_empty include/linux/list.h:292 [inline]
BUG: KASAN: use-after-free in driver_deferred_probe_del+0x63/0x240 drivers/base/dd.c:148
Read of size 8 at addr ffff88802fd930e0 by task syz.3.31/4498

CPU: 1 PID: 4498 Comm: syz.3.31 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:420
 kasan_report+0x10b/0x140 mm/kasan/report.c:524
 list_empty include/linux/list.h:292 [inline]
 driver_deferred_probe_del+0x63/0x240 drivers/base/dd.c:148
 device_del+0x64f/0xa80 drivers/base/core.c:3902
 usb_del_gadget+0x18c/0x250 drivers/usb/gadget/udc/core.c:1580
 usb_del_gadget_udc+0x11/0x30 drivers/usb/gadget/udc/core.c:1603
 dummy_udc_remove+0x54/0x60 drivers/usb/gadget/udc/dummy_hcd.c:1141
 platform_remove+0x92/0xe0 drivers/base/platform.c:1422
 device_remove drivers/base/dd.c:547 [inline]
 __device_release_driver drivers/base/dd.c:1279 [inline]
 device_release_driver_internal+0x47d/0x7c0 drivers/base/dd.c:1305
 unbind_store+0x2e2/0x300 drivers/base/bus.c:193
 kernfs_fop_write_iter+0x3a0/0x520 fs/kernfs/file.c:352
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x482/0x9a0 fs/read_write.c:584
 ksys_write+0x14d/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc06499e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff4889ef68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fc064c25fa0 RCX: 00007fc06499e0d9
RDX: 000000000000000b RSI: 0000200000000400 RDI: 0000000000000003
RBP: 00007fc064a35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc064c25fac R14: 00007fc064c25fa0 R15: 00007fc064c25fa0
 </TASK>

Allocated by task 4496:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:384
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 device_private_init drivers/base/core.c:3541 [inline]
 device_add+0xb2/0x1050 drivers/base/core.c:3591
 usb_add_gadget+0x47c/0x6f0 drivers/usb/gadget/udc/core.c:1450
 usb_add_gadget_udc_release+0x198/0x1e0 drivers/usb/gadget/udc/core.c:1506
 dummy_udc_probe+0x686/0x780 drivers/usb/gadget/udc/dummy_hcd.c:1120
 platform_probe+0x137/0x1c0 drivers/base/platform.c:1400
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x24a/0xb40 drivers/base/dd.c:638
 __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:804
 device_driver_attach+0xd9/0x1c0 drivers/base/dd.c:1131
 bind_store+0x33b/0x380 drivers/base/bus.c:216
 kernfs_fop_write_iter+0x3a0/0x520 fs/kernfs/file.c:352
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x482/0x9a0 fs/read_write.c:584
 ksys_write+0x14d/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 4498:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x133/0x1b0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xb6/0x200 mm/slub.c:3700
 kobject_cleanup lib/kobject.c:681 [inline]
 kobject_release lib/kobject.c:712 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x217/0x450 lib/kobject.c:729
 bus_remove_device+0x2bf/0x400 drivers/base/bus.c:527
 device_del+0x63f/0xa80 drivers/base/core.c:3900
 usb_del_gadget+0x18c/0x250 drivers/usb/gadget/udc/core.c:1580
 usb_del_gadget_udc+0x11/0x30 drivers/usb/gadget/udc/core.c:1603
 dummy_udc_remove+0x54/0x60 drivers/usb/gadget/udc/dummy_hcd.c:1141
 platform_remove+0x92/0xe0 drivers/base/platform.c:1422
 device_remove drivers/base/dd.c:547 [inline]
 __device_release_driver drivers/base/dd.c:1279 [inline]
 device_release_driver_internal+0x47d/0x7c0 drivers/base/dd.c:1305
 unbind_store+0x2e2/0x300 drivers/base/bus.c:193
 kernfs_fop_write_iter+0x3a0/0x520 fs/kernfs/file.c:352
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x482/0x9a0 fs/read_write.c:584
 ksys_write+0x14d/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88802fd93000
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 224 bytes inside of
 512-byte region [ffff88802fd93000, ffff88802fd93200)

The buggy address belongs to the physical page:
page:ffffea0000bf6400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2fd90
head:ffffea0000bf6400 order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000001 ffff888017441c80
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 21081982765, free_ts 0
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2560
 prep_new_page mm/page_alloc.c:2567 [inline]
 get_page_from_freelist+0x206b/0x2180 mm/page_alloc.c:4358
 __alloc_pages+0x1ec/0x4f0 mm/page_alloc.c:5658
 alloc_page_interleave+0x24/0x1e0 mm/mempolicy.c:2115
 alloc_slab_page+0x5d/0x180 mm/slub.c:1799
 allocate_slab mm/slub.c:1944 [inline]
 new_slab+0x87/0x2d0 mm/slub.c:1997
 ___slab_alloc+0xbc5/0x1240 mm/slub.c:3154
 __slab_alloc mm/slub.c:3240 [inline]
 slab_alloc_node mm/slub.c:3325 [inline]
 __kmem_cache_alloc_node+0x126/0x270 mm/slub.c:3398
 __do_kmalloc_node mm/slab_common.c:935 [inline]
 __kmalloc_node_track_caller+0xa0/0x240 mm/slab_common.c:956
 kmalloc_reserve net/core/skbuff.c:446 [inline]
 __alloc_skb+0x226/0x7d0 net/core/skbuff.c:515
 alloc_skb include/linux/skbuff.h:1303 [inline]
 alloc_uevent_skb+0x7d/0x230 lib/kobject_uevent.c:290
 uevent_net_broadcast_tagged lib/kobject_uevent.c:351 [inline]
 kobject_uevent_net_broadcast+0x17e/0x530 lib/kobject_uevent.c:412
 kobject_uevent_env+0x555/0x890 lib/kobject_uevent.c:608
 netdev_queue_add_kobject net/core/net-sysfs.c:1675 [inline]
 netdev_queue_update_kobjects+0x238/0x480 net/core/net-sysfs.c:1716
 register_queue_kobjects net/core/net-sysfs.c:1777 [inline]
 netdev_register_kobject+0x273/0x320 net/core/net-sysfs.c:2017
 register_netdevice+0x133a/0x1b80 net/core/dev.c:10243
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88802fd92f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802fd93000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802fd93080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff88802fd93100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802fd93180: fb fb fb fb fb 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
2026/08/20 11:14 linux-6.1.y 7e6e67054721 1e72964b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in driver_deferred_probe_del
2026/07/31 05:08 linux-6.1.y fb28aa725e05 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in driver_deferred_probe_del
* Struck through repros no longer work on HEAD.