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

Status: upstream: reported on 2026/07/31 01:35
Subsystems: kernel
Labels: prio:normal actionable
[Documentation on labels]
Reported-by: syzbot+d65a1f23d3bb8e21ffb5@syzkaller.appspotmail.com
First crash: 55d, last: 28d
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
ed8cfb1a moderation Actionable: ✅ ❓ KASAN: slab-use-after-free Read in raw_ioctl 2026/07/31 01:18 2026/07/31 01:18 2026/07/31 01:34 aaffb173
9b528c51 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KASAN: slab-use-after-free Read in raw_ioctl 2026/07/28 01:19 2026/07/28 01:19 2026/07/28 01:38 4cb2b096
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kernel?] KASAN: slab-use-after-free Read in raw_ioctl 0 (1) 2026/07/31 01:35
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-12 KASAN: slab-use-after-free Read in raw_ioctl 19 syz, C 8 10d 54d 0/1 premoderation: reported C repro on 2026/07/27 05:09
linux-6.1 KASAN: use-after-free Read in raw_ioctl 19 syz error 2 47d 47d 0/3 upstream: reported syz repro on 2026/08/03 07:13
upstream KMSAN: kernel-infoleak in raw_ioctl (2) usb 9 syz, C 18201 722d 788d 28/29 fixed on 2024/10/22 11:57
android-6-1 KASAN: use-after-free Read in raw_ioctl 19 4 28d 53d 0/2 premoderation: reported on 2026/07/28 02:22

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in string_nocheck lib/vsprintf.c:648 [inline]
BUG: KASAN: slab-use-after-free in string+0x471/0x4d0 lib/vsprintf.c:730
Read of size 1 at addr ffff88802d1090e0 by task syz.0.52/6007

CPU: 1 UID: 0 PID: 6007 Comm: syz.0.52 Tainted: G             L      syzkaller #0 PREEMPT(full) 
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
 string_nocheck lib/vsprintf.c:648 [inline]
 string+0x471/0x4d0 lib/vsprintf.c:730
 vsnprintf+0x422/0x1300 lib/vsprintf.c:2945
 snprintf+0xc7/0x100 lib/vsprintf.c:3043
 set_dev_info drivers/base/core.c:4984 [inline]
 dev_vprintk_emit+0x375/0x3e0 drivers/base/core.c:4994
 dev_printk_emit+0xd2/0x10d drivers/base/core.c:5007
 __dev_printk+0xcb/0x100 drivers/base/core.c:5019
 _dev_err+0xef/0x127 drivers/base/core.c:5062
 raw_ioctl_ep_enable drivers/usb/gadget/legacy/raw_gadget.c:887 [inline]
 raw_ioctl.cold+0x10e/0x3a6 drivers/usb/gadget/legacy/raw_gadget.c:1319
 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: 0033:0x7fd98e79dd6b
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
RSP: 002b:00007fd98f6dbef0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd98eb50320 RCX: 00007fd98e79dd6b
RDX: 00007fd98eb5034c RSI: 0000000040095505 RDI: 0000000000000004
RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000007
R10: 0000000000000004 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd98eb50530 R14: 0000000000000000 R15: 00007fd98eb5034e
 </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]
 __do_kmalloc_node mm/slub.c:5334 [inline]
 __kmalloc_node_track_caller_noprof+0x331/0x830 mm/slub.c:5471
 kvasprintf+0xbc/0x150 lib/kasprintf.c:25
 kvasprintf_const+0x66/0x1a0 lib/kasprintf.c:49
 kobject_set_name_vargs+0x5a/0x140 lib/kobject.c:274
 dev_set_name+0xc7/0x100 drivers/base/core.c:3560
 usb_add_gadget+0x520/0x920 drivers/usb/gadget/udc/core.c:1459
 usb_add_gadget_udc_release drivers/usb/gadget/udc/core.c:1517 [inline]
 usb_add_gadget_udc+0x26/0x70 drivers/usb/gadget/udc/core.c:1564
 dummy_udc_probe+0x69e/0x960 drivers/usb/gadget/udc/dummy_hcd.c:1121
 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+0x803/0xc00 drivers/usb/gadget/udc/dummy_hcd.c:2894
 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 6031:
 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
 kfree_const+0x5a/0x70 mm/util.c:46
 kobject_cleanup lib/kobject.c:695 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x218/0x640 lib/kobject.c:737
 put_device+0x1f/0x30 drivers/base/core.c:3880
 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

The buggy address belongs to the object at ffff88802d1090e0
 which belongs to the cache kmalloc-16 of size 16
The buggy address is located 0 bytes inside of
 freed 16-byte region [ffff88802d1090e0, ffff88802d1090f0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2d109
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801c022640 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800800080 00000000f5000000 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 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 8461766621, free_ts 8461250068
 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_node_track_caller_noprof+0x679/0x830 mm/slub.c:5471
 kvasprintf+0xbc/0x150 lib/kasprintf.c:25
 kvasprintf_const+0x66/0x1a0 lib/kasprintf.c:49
 kobject_set_name_vargs+0x5a/0x140 lib/kobject.c:274
 dev_set_name+0xc7/0x100 drivers/base/core.c:3560
 usb_set_configuration+0xb15/0x1c60 drivers/usb/core/message.c:2203
 usb_generic_driver_probe+0xa1/0xe0 drivers/usb/core/generic.c:250
 usb_probe_device+0xef/0x400 drivers/usb/core/driver.c:291
 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
page last free pid 95 tgid 95 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1406 [inline]
 __free_frozen_pages+0x79f/0x1090 mm/page_alloc.c:2950
 __kasan_populate_vmalloc_do mm/kasan/shadow.c:393 [inline]
 __kasan_populate_vmalloc+0x1ea/0x210 mm/kasan/shadow.c:424
 kasan_populate_vmalloc include/linux/kasan.h:580 [inline]
 alloc_vmap_area+0x95d/0x2bb0 mm/vmalloc.c:2145
 __get_vm_area_node+0x1ca/0x330 mm/vmalloc.c:3248
 __vmalloc_node_range_noprof+0x228/0x1630 mm/vmalloc.c:4064
 __vmalloc_node_noprof+0xad/0xf0 mm/vmalloc.c:4165
 alloc_thread_stack_node kernel/fork.c:359 [inline]
 dup_task_struct kernel/fork.c:929 [inline]
 copy_process+0x7fb/0x8030 kernel/fork.c:2115
 kernel_clone+0x176/0x9d0 kernel/fork.c:2748
 user_mode_thread+0xcc/0x110 kernel/fork.c:2824
 call_usermodehelper_exec_work kernel/umh.c:171 [inline]
 call_usermodehelper_exec_work+0xcb/0x180 kernel/umh.c:157
 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

Memory state around the buggy address:
 ffff88802d108f80: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
 ffff88802d109000: 00 04 fc fc 00 00 fc fc 00 04 fc fc 00 04 fc fc
>ffff88802d109080: 00 04 fc fc 00 01 fc fc 00 01 fc fc fa fb fc fc
                                                       ^
 ffff88802d109100: 00 04 fc fc 00 04 fc fc fa fb fc fc fa fb fc fc
 ffff88802d109180: 00 04 fc fc 00 00 fc fc 00 04 fc fc 00 04 fc fc
==================================================================

Crashes (12):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/17 02:24 upstream dcb68831eac7 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in raw_ioctl
2026/08/09 12:20 upstream 06cf61899d64 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in raw_ioctl
2026/08/06 15:35 upstream 0d8395707651 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in raw_ioctl
2026/07/29 04:53 upstream 3b5f4b83c4ab 19622d9d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in raw_ioctl
2026/08/22 03:42 upstream 818bebeb63dd 1e72964b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in raw_ioctl
2026/08/22 03:42 upstream 818bebeb63dd 1e72964b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in raw_ioctl
2026/08/17 20:28 upstream 8d3ae59288f1 905244d6 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in raw_ioctl
2026/08/05 21:35 upstream c21bb4193868 1eed00d1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in raw_ioctl
2026/07/26 12:49 upstream 3dab139d4795 4a865b71 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in raw_ioctl
2026/08/17 07:37 upstream dcb68831eac7 746171ee .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 KASAN: slab-use-after-free Read in raw_ioctl
2026/08/21 03:31 linux-next 7079a12d7506 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in raw_ioctl
2026/08/18 08:19 linux-next e6664f2b33db 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce KASAN: slab-use-after-free Read in raw_ioctl
* Struck through repros no longer work on HEAD.