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

Status: premoderation: reported C repro on 2026/07/27 05:09
Reported-by: syzbot+947390c98c879921cc3f@syzkaller.appspotmail.com
First crash: 11d, last: 5d06h
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Read in raw_ioctl kernel prio:normal actionable 19 4 1d10h 8d00h 0/29 upstream: reported on 2026/07/31 01:35
linux-6.1 KASAN: use-after-free Read in raw_ioctl 19 syz 2 4d13h 4d19h 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 679d 745d 28/29 fixed on 2024/10/22 11:57
android-6-1 KASAN: use-after-free Read in raw_ioctl 19 1 11d 11d 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:646 [inline]
BUG: KASAN: slab-use-after-free in string+0x20f/0x2b0 lib/vsprintf.c:728
Read of size 1 at addr ffff888105ff3b80 by task syz.0.17/407

CPU: 0 UID: 0 PID: 407 Comm: syz.0.17 Not tainted syzkaller #0 a4a563d0c71b2f3eba821a1af94cbf4bdc8174ca
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
 print_address_description+0x71/0x210 mm/kasan/report.c:377
 print_report+0x4a/0x70 mm/kasan/report.c:481
 kasan_report+0x162/0x1a0 mm/kasan/report.c:594
 __asan_report_load1_noabort+0x18/0x20 mm/kasan/report_generic.c:378
 string_nocheck lib/vsprintf.c:646 [inline]
 string+0x20f/0x2b0 lib/vsprintf.c:728
 vsnprintf+0xe65/0x1ad0 lib/vsprintf.c:2803
 snprintf+0xe9/0x140 lib/vsprintf.c:2938
 set_dev_info drivers/base/core.c:4950 [inline]
 dev_vprintk_emit+0x313/0x400 drivers/base/core.c:4960
 dev_printk_emit+0xef/0x150 drivers/base/core.c:4973
 __dev_printk+0x17f/0x1b0 drivers/base/core.c:4985
 _dev_err+0x11f/0x180 drivers/base/core.c:5028
 raw_ioctl_ep0_stall drivers/usb/gadget/legacy/raw_gadget.c:827 [inline]
 raw_ioctl+0x2929/0x37a0 drivers/usb/gadget/legacy/raw_gadget.c:1340
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0x132/0x1b0 fs/ioctl.c:893
 __x64_sys_ioctl+0x7f/0xa0 fs/ioctl.c:893
 x64_sys_call+0x1878/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7ff4c239db2b
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:00007fffb93fa610 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007ff4c239db2b
RDX: 0000000000000000 RSI: 000000000000550c RDI: 0000000000000003
RBP: 00007ff4c2433eaf R08: 0000000000000003 R09: 0000000000000409
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
R13: 0000200000000080 R14: 00007ff4c2625fa0 R15: 00007ff4c2625fa0
 </TASK>

Allocated by task 1:
 kasan_save_stack mm/kasan/common.c:49 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:70
 kasan_save_alloc_info+0x3a/0x50 mm/kasan/generic.c:565
 poison_kmalloc_redzone mm/kasan/common.c:379 [inline]
 __kasan_kmalloc+0x96/0xb0 mm/kasan/common.c:396
 kasan_kmalloc include/linux/kasan.h:261 [inline]
 __do_kmalloc_node mm/slub.c:4395 [inline]
 __kmalloc_node_track_caller_noprof+0x24e/0x4f0 mm/slub.c:4414
 kvasprintf+0xf1/0x260 lib/kasprintf.c:25
 kvasprintf_const+0xf6/0x250 lib/kasprintf.c:49
 kobject_set_name_vargs+0x65/0x120 lib/kobject.c:274
 dev_set_name+0xe3/0x140 drivers/base/core.c:3495
 usb_add_gadget+0x3e1/0x6e0 drivers/usb/gadget/udc/core.c:1425
 usb_add_gadget_udc_release drivers/usb/gadget/udc/core.c:1477 [inline]
 usb_add_gadget_udc+0x11e/0x160 drivers/usb/gadget/udc/core.c:1524
 dummy_udc_probe+0x6ea/0x7f0 drivers/usb/gadget/udc/dummy_hcd.c:1102
 platform_probe+0x17a/0x200 drivers/base/platform.c:1404
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x2e1/0x8b0 drivers/base/dd.c:657
 __driver_probe_device+0x193/0x280 drivers/base/dd.c:799
 driver_probe_device+0x54/0x3f0 drivers/base/dd.c:829
 __device_attach_driver+0x2f1/0x4b0 drivers/base/dd.c:957
 bus_for_each_drv+0x264/0x300 drivers/base/bus.c:459
 __device_attach+0x2c4/0x3c0 drivers/base/dd.c:1029
 device_initial_probe+0x1e/0x30 drivers/base/dd.c:1078
 bus_probe_device+0x18b/0x270 drivers/base/bus.c:534
 device_add+0x7fd/0xbf0 drivers/base/core.c:3692
 platform_device_add+0x464/0x6c0 drivers/base/platform.c:716
 dummy_hcd_init+0xce2/0x1230 drivers/usb/gadget/udc/dummy_hcd.c:2876
 do_one_initcall+0x1e8/0x6a0 init/main.c:1406
 do_initcall_level+0x174/0x2e5 init/main.c:1468
 do_initcalls+0x7e/0x160 init/main.c:1484
 do_basic_setup+0x95/0xb0 init/main.c:1503
 kernel_init_freeable+0x2b1/0x400 init/main.c:1717
 kernel_init+0x21/0x1e0 init/main.c:1606
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Freed by task 400:
 kasan_save_stack mm/kasan/common.c:49 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:70
 kasan_save_free_info+0x44/0x50 mm/kasan/generic.c:579
 poison_slab_object mm/kasan/common.c:249 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:266
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2445 [inline]
 slab_free mm/slub.c:4714 [inline]
 kfree+0x158/0x440 mm/slub.c:4875
 kfree_const+0x3d/0x50 mm/util.c:49
 kobject_cleanup lib/kobject.c:695 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x21f/0x2a0 lib/kobject.c:737
 put_device+0x23/0x40 drivers/base/core.c:3800
 usb_put_gadget include/linux/usb/gadget.h:512 [inline]
 usb_del_gadget_udc+0x25/0x30 drivers/usb/gadget/udc/core.c:1567
 dummy_udc_remove+0x5c/0x70 drivers/usb/gadget/udc/dummy_hcd.c:1123
 platform_remove+0x7e/0xb0 drivers/base/platform.c:1424
 device_remove drivers/base/dd.c:567 [inline]
 __device_release_driver drivers/base/dd.c:1272 [inline]
 device_release_driver_internal+0x4ad/0x830 drivers/base/dd.c:1295
 device_driver_detach+0x3f/0x50 drivers/base/dd.c:1331
 unbind_store+0x1ab/0x1f0 drivers/base/bus.c:244
 drv_attr_store+0x91/0xb0 drivers/base/bus.c:125
 sysfs_kf_write+0x141/0x160 fs/sysfs/file.c:136
 kernfs_fop_write_iter+0x316/0x510 fs/kernfs/file.c:352
 new_sync_write fs/read_write.c:591 [inline]
 vfs_write+0x762/0xfd0 fs/read_write.c:684
 ksys_write+0x145/0x260 fs/read_write.c:737
 __do_sys_write fs/read_write.c:749 [inline]
 __se_sys_write fs/read_write.c:746 [inline]
 __x64_sys_write+0x7f/0x90 fs/read_write.c:746
 x64_sys_call+0x271c/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

The buggy address belongs to the object at ffff888105ff3b80
 which belongs to the cache kmalloc-16 of size 16
The buggy address is located 0 bytes inside of
 freed 16-byte region [ffff888105ff3b80, ffff888105ff3b90)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x105ff3
flags: 0x4000000000000000(zone=1)
page_type: f5(slab)
raw: 4000000000000000 ffff888100041640 ffffea000422d940 dead000000000002
raw: 0000000000000000 0000000000800080 00000001f5000000 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 0xd2c00(GFP_NOIO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 4046773052, free_ts 0
 create_dummy_stack mm/page_owner.c:93 [inline]
 register_dummy_stack+0x99/0x110 mm/page_owner.c:99
 init_page_owner+0x36/0x840 mm/page_owner.c:117
 invoke_init_callbacks mm/page_ext.c:152 [inline]
 page_ext_init+0x3f8/0x44b mm/page_ext.c:501
 mm_core_init+0x4b/0x7b mm/mm_init.c:2670
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888105ff3a80: 00 01 fc fc 00 01 fc fc 00 01 fc fc fa fb fc fc
 ffff888105ff3b00: 00 01 fc fc 00 00 fc fc fa fb fc fc fa fb fc fc
>ffff888105ff3b80: fa fb fc fc 00 01 fc fc 00 05 fc fc 00 04 fc fc
                   ^
 ffff888105ff3c00: 00 00 fc fc 00 01 fc fc 00 01 fc fc 00 00 fc fc
 ffff888105ff3c80: fa fb fc fc fa fb fc fc 00 00 fc fc fa fb fc fc
==================================================================
gadget €gŪˆ˙˙: fail, usb_ep_set_halt returned -108

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/27 05:09 android16-6.12 579215f16d4e 492bab15 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in raw_ioctl
2026/08/02 19:41 android16-6.12 1a138e24e292 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in raw_ioctl
2026/08/01 13:07 android16-6.12 1a138e24e292 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in raw_ioctl
* Struck through repros no longer work on HEAD.