KASAN: slab-use-after-free Read in i2c_adapter_lock_bus

Status: upstream: reported on 2026/08/02 00:01
Subsystems: i2c
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+450abcfc7906fe1a1e16@syzkaller.appspotmail.com
First crash: 13d, last: 22m
▶ ▼ ✨ AI Jobs (4)
ID Workflow Result Correct Bug Created Started Finished Revision
74faacfb repro-c Reproduced: ✅
❓ KASAN: slab-use-after-free Read in i2c_adapter_lock_bus 2026/08/07 14:11 2026/08/07 14:11 2026/08/07 22:02 e4ef95d6
bc157b1f moderation Actionable: ❌ ❓ KASAN: slab-use-after-free Read in i2c_adapter_lock_bus 2026/07/31 00:56 2026/07/31 00:56 2026/07/31 02:49 aaffb173
ef5baa3e repro 💥 KASAN: slab-use-after-free Read in i2c_adapter_lock_bus 2026/07/30 11:51 2026/07/30 11:51 2026/07/30 13:36 2377cd3d
e38f00e1 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KASAN: slab-use-after-free Read in i2c_adapter_lock_bus 2026/07/28 00:58 2026/07/28 00:58 2026/07/28 01:39 4cb2b096
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [i2c?] KASAN: slab-use-after-free Read in i2c_adapter_lock_bus 0 (1) 2026/08/02 00:01
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/08/08 08:25 nogikh@google.com upstream pending

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in i2c_adapter_depth drivers/i2c/i2c-core-base.c:1243 [inline]
BUG: KASAN: slab-use-after-free in i2c_adapter_lock_bus+0xe0/0x100 drivers/i2c/i2c-core-base.c:849
Read of size 8 at addr ffff88802a4b8108 by task syz.2.9893/28591

CPU: 1 UID: 0 PID: 28591 Comm: syz.2.9893 Tainted: G             L      syzkaller #0 PREEMPT(lazy) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x13d/0x4b0 mm/kasan/report.c:482
 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
 i2c_adapter_depth drivers/i2c/i2c-core-base.c:1243 [inline]
 i2c_adapter_lock_bus+0xe0/0x100 drivers/i2c/i2c-core-base.c:849
 i2c_lock_bus include/linux/i2c.h:809 [inline]
 __i2c_lock_bus_helper drivers/i2c/i2c-core.h:47 [inline]
 i2c_smbus_xfer+0x268/0x3c0 drivers/i2c/i2c-core-smbus.c:543
 i2cdev_ioctl_smbus+0x233/0xac0 drivers/i2c/i2c-dev.c:389
 i2cdev_ioctl+0x3cf/0x830 drivers/i2c/i2c-dev.c:478
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f826019e0d9
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:00007f826114f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f8260425fa0 RCX: 00007f826019e0d9
RDX: 0000200000000100 RSI: 0000000000000720 RDI: 0000000000000004
RBP: 00007f8260235024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8260426038 R14: 00007f8260425fa0 R15: 00007fffd25ac848
 </TASK>

Allocated by task 1:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x2e5/0x6c0 mm/slub.c:5489
 _kmalloc_noprof include/linux/slab.h:988 [inline]
 _kzalloc_noprof include/linux/slab.h:1309 [inline]
 usb_alloc_dev+0x55/0x1090 drivers/usb/core/usb.c:651
 usb_add_hcd.cold+0x257/0x1158 drivers/usb/core/hcd.c:2880
 dummy_hcd_probe+0x189/0x2fa drivers/usb/gadget/udc/dummy_hcd.c:2722
 platform_probe+0x106/0x1d0 drivers/base/platform.c:1439
 call_driver_probe drivers/base/dd.c:628 [inline]
 really_probe+0x241/0xa60 drivers/base/dd.c:706
 __driver_probe_device+0x20e/0x450 drivers/base/dd.c:868
 driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
 __device_attach_driver+0x1df/0x320 drivers/base/dd.c:1026
 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:500
 __device_attach+0x1e4/0x4d0 drivers/base/dd.c:1098
 device_initial_probe+0xaf/0xd0 drivers/base/dd.c:1153
 bus_probe_device+0x64/0x160 drivers/base/bus.c:620
 device_add+0x121d/0x1970 drivers/base/core.c:3772
 platform_device_add+0x35a/0x800 drivers/base/platform.c:762
 dummy_hcd_init+0x5eb/0xc00 drivers/usb/gadget/udc/dummy_hcd.c:2873
 do_one_initcall+0x11d/0x700 init/main.c:1347
 do_initcall_level init/main.c:1409 [inline]
 do_initcalls init/main.c:1425 [inline]
 do_basic_setup init/main.c:1445 [inline]
 kernel_init_freeable+0x6ea/0x7b0 init/main.c:1658
 kernel_init+0x1f/0x1e0 init/main.c:1548
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 28404:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2677 [inline]
 slab_free mm/slub.c:6377 [inline]
 kfree+0x22b/0x6c0 mm/slub.c:6692
 device_release+0xd2/0x270 drivers/base/core.c:2636
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1f7/0x640 lib/kobject.c:737
 put_device+0x1f/0x30 drivers/base/core.c:3880
 usb_put_dev+0x23/0x30 drivers/usb/core/usb.c:790
 usb_put_invalidate_rhdev drivers/usb/core/hcd.c:2769 [inline]
 usb_remove_hcd.cold+0x307/0x401 drivers/usb/core/hcd.c:3090
 dummy_hcd_remove+0x109/0x1e0 drivers/usb/gadget/udc/dummy_hcd.c:2761
 platform_remove+0x5f/0x80 drivers/base/platform.c:1456
 device_remove+0xcb/0x180 drivers/base/dd.c:616
 __device_release_driver drivers/base/dd.c:1349 [inline]
 device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
 unbind_store+0xf8/0x110 drivers/base/bus.c:244
 drv_attr_store+0x74/0xb0 drivers/base/bus.c:125
 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6ac/0x1050 fs/read_write.c:687
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Last potentially related work creation:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:556
 insert_work+0x36/0x230 kernel/workqueue.c:2226
 __queue_work+0x9bc/0x12b0 kernel/workqueue.c:2401
 queue_work_on+0x1a9/0x1e0 kernel/workqueue.c:2452
 queue_work include/linux/workqueue.h:699 [inline]
 rpm_idle+0x700/0x790 drivers/base/power/runtime.c:537
 rpm_suspend+0xf73/0x11a0 drivers/base/power/runtime.c:729
 rpm_idle+0x60c/0x790 drivers/base/power/runtime.c:562
 __pm_runtime_idle+0xba/0x1a0 drivers/base/power/runtime.c:1129
 hub_event+0xe0d/0x4a60 drivers/usb/core/hub.c:5995
 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
 process_scheduled_works kernel/workqueue.c:3405 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Second to last potentially related work creation:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:556
 insert_work+0x36/0x230 kernel/workqueue.c:2226
 __queue_work+0x9bc/0x12b0 kernel/workqueue.c:2401
 queue_work_on+0x1a9/0x1e0 kernel/workqueue.c:2452
 queue_work include/linux/workqueue.h:699 [inline]
 rpm_idle+0x700/0x790 drivers/base/power/runtime.c:537
 rpm_suspend+0xf73/0x11a0 drivers/base/power/runtime.c:729
 rpm_idle+0x60c/0x790 drivers/base/power/runtime.c:562
 __pm_runtime_idle+0xba/0x1a0 drivers/base/power/runtime.c:1129
 hub_event+0xe0d/0x4a60 drivers/usb/core/hub.c:5995
 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
 process_scheduled_works kernel/workqueue.c:3405 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff88802a4b8000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 264 bytes inside of
 freed 2048-byte region [ffff88802a4b8000, ffff88802a4b8800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88802a4b8000 pfn:0x2a4b8
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff88813fe22000 ffffea00008ea810 ffffea0001eae410
raw: ffff88802a4b8000 0000000800080005 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff88813fe22000 ffffea00008ea810 ffffea0001eae410
head: ffff88802a4b8000 0000000800080005 00000000f5000000 0000000000000000
head: 00fff00000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 184, tgid 184 (kworker/u8:6), ts 5909777501, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1859
 prep_new_page mm/page_alloc.c:1867 [inline]
 get_page_from_freelist+0xf48/0x3530 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x299/0x2dc0 mm/page_alloc.c:5304
 alloc_slab_page mm/slub.c:3266 [inline]
 allocate_slab mm/slub.c:3380 [inline]
 new_slab+0xa2/0x640 mm/slub.c:3426
 refill_objects+0xe3/0x410 mm/slub.c:7310
 refill_sheaf mm/slub.c:2804 [inline]
 __pcs_replace_empty_main+0x376/0x680 mm/slub.c:4675
 alloc_from_pcs mm/slub.c:4773 [inline]
 slab_alloc_node mm/slub.c:4905 [inline]
 __do_kmalloc_node mm/slub.c:5333 [inline]
 __kmalloc_noprof+0x66d/0x820 mm/slub.c:5359
 _kmalloc_noprof include/linux/slab.h:992 [inline]
 _kzalloc_noprof include/linux/slab.h:1309 [inline]
 scsi_alloc_target+0x12f/0xc70 drivers/scsi/scsi_scan.c:505
 __scsi_scan_target+0x124/0x570 drivers/scsi/scsi_scan.c:1780
 scsi_scan_channel drivers/scsi/scsi_scan.c:1885 [inline]
 scsi_scan_channel+0x13d/0x1e0 drivers/scsi/scsi_scan.c:1861
 scsi_scan_host_selected+0x2fe/0x3e0 drivers/scsi/scsi_scan.c:1914
 do_scsi_scan_host+0x1f4/0x270 drivers/scsi/scsi_scan.c:2047
 do_scan_async+0x42/0x480 drivers/scsi/scsi_scan.c:2057
 async_run_entry_fn+0x9f/0x580 kernel/async.c:129
 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
 process_scheduled_works kernel/workqueue.c:3405 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88802a4b8000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802a4b8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802a4b8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88802a4b8180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802a4b8200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/08 03:29 upstream 9a143525f62b e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in i2c_adapter_lock_bus
2026/08/03 05:40 upstream bd1dde877520 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in i2c_adapter_lock_bus
2026/08/01 08:07 upstream 0131b508c0e2 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root KASAN: slab-use-after-free Read in i2c_adapter_lock_bus
2026/07/29 17:56 upstream fc02acf6ac0c cb1587ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-use-after-free Read in i2c_adapter_lock_bus
2026/07/27 15:15 upstream f5098b6bae76 4cb2b096 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root KASAN: slab-use-after-free Read in i2c_adapter_lock_bus
2026/07/26 23:02 upstream 4235cb24ec1e 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in i2c_adapter_lock_bus
2026/08/08 10:44 linux-next cc2b5f627e8c e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce KASAN: slab-use-after-free Read in i2c_adapter_lock_bus
2026/07/26 03:42 linux-next cc2b5f627e8c 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce KASAN: slab-use-after-free Read in i2c_adapter_lock_bus
* Struck through repros no longer work on HEAD.