syzbot
KASAN: use-after-free Read in device_create
Status:
premoderation: reported on 2026/07/25 07:17
Reported-by: syzbot+037bb524b85268c80ead@syzkaller.appspotmail.com
First crash: 18d, last: 2d20h
Sample crash report:
==================================================================
BUG: KASAN: use-after-free in kobject_get+0x113/0x120 lib/kobject.c:631
Read of size 1 at addr ffff88810d70d03c by task syz.5.200/1117
CPU: 0 PID: 1117 Comm: syz.5.200 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
<TASK>
__dump_stack+0x21/0x24 lib/dump_stack.c:88
dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
print_address_description+0x71/0x200 mm/kasan/report.c:316
print_report+0x4a/0x60 mm/kasan/report.c:420
kasan_report+0x122/0x150 mm/kasan/report.c:524
__asan_report_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:348
kobject_get+0x113/0x120 lib/kobject.c:631
get_device drivers/base/core.c:3794 [inline]
device_add+0x2f0/0xec0 drivers/base/core.c:3618
device_create_groups_vargs drivers/base/core.c:4392 [inline]
device_create+0x26c/0x300 drivers/base/core.c:4434
create_function_device+0x60/0x70 drivers/usb/gadget/configfs.c:36
create_alsa_device drivers/usb/gadget/function/f_midi.c:1306 [inline]
f_midi_alloc_inst+0x1a8/0x380 drivers/usb/gadget/function/f_midi.c:1347
try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline]
usb_get_function_instance+0xf3/0x310 drivers/usb/gadget/functions.c:44
function_make+0x118/0x360 drivers/usb/gadget/configfs.c:652
configfs_mkdir+0x518/0x9e0 fs/configfs/dir.c:1329
vfs_mkdir+0x39c/0x580 fs/namei.c:4113
do_mkdirat+0x174/0x4d0 fs/namei.c:4138
__do_sys_mkdirat fs/namei.c:4153 [inline]
__se_sys_mkdirat fs/namei.c:4151 [inline]
__x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4151
x64_sys_call+0x73d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:259
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: 0033:0x7f45fcd9e0d9
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:00007f45fdcea028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f45fd026090 RCX: 00007f45fcd9e0d9
RDX: 00000000000001ff RSI: 00002000000003c0 RDI: ffffffffffffff9c
RBP: 00007f45fce35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f45fd026128 R14: 00007f45fd026090 R15: 00007ffd8dc720f8
</TASK>
Allocated by task 91:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
kasan_save_alloc_info+0x1f/0x30 mm/kasan/generic.c:505
____kasan_kmalloc mm/kasan/common.c:380 [inline]
__kasan_kmalloc+0x95/0xb0 mm/kasan/common.c:389
kasan_kmalloc include/linux/kasan.h:212 [inline]
kmalloc_trace+0x40/0xb0 mm/slab_common.c:1033
kmalloc include/linux/slab.h:563 [inline]
syslog_print+0x11f/0x600 kernel/printk/printk.c:1502
do_syslog+0x6e1/0x7a0 kernel/printk/printk.c:1681
__do_sys_syslog kernel/printk/printk.c:1773 [inline]
__se_sys_syslog kernel/printk/printk.c:1771 [inline]
__x64_sys_syslog+0x7c/0x90 kernel/printk/printk.c:1771
x64_sys_call+0x610/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:104
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 91:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:516
____kasan_slab_free+0x132/0x180 mm/kasan/common.c:242
__kasan_slab_free+0x11/0x20 mm/kasan/common.c:250
kasan_slab_free include/linux/kasan.h:178 [inline]
slab_free_hook mm/slub.c:1750 [inline]
slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1776
slab_free mm/slub.c:3712 [inline]
__kmem_cache_free+0xb7/0x1b0 mm/slub.c:3728
kfree+0x6f/0xf0 mm/slab_common.c:990
syslog_print+0x568/0x600 kernel/printk/printk.c:1594
do_syslog+0x6e1/0x7a0 kernel/printk/printk.c:1681
__do_sys_syslog kernel/printk/printk.c:1773 [inline]
__se_sys_syslog kernel/printk/printk.c:1771 [inline]
__x64_sys_syslog+0x7c/0x90 kernel/printk/printk.c:1771
x64_sys_call+0x610/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:104
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 ffff88810d70d000
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 60 bytes inside of
1024-byte region [ffff88810d70d000, ffff88810d70d400)
The buggy address belongs to the physical page:
page:ffffea000435c200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10d708
head:ffffea000435c200 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 dead000000000001 ffff888100043080
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
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 1, tgid 1 (swapper/0), ts 2330441887, free_ts 0
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2672
prep_new_page+0x1c/0x110 mm/page_alloc.c:2679
get_page_from_freelist+0x2ca9/0x2d20 mm/page_alloc.c:4586
__alloc_pages+0x1fa/0x610 mm/page_alloc.c:5930
alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
allocate_slab mm/slub.c:1967 [inline]
new_slab+0x98/0x3e0 mm/slub.c:2020
___slab_alloc+0x70f/0xb70 mm/slub.c:3177
__slab_alloc+0x5e/0xa0 mm/slub.c:3263
slab_alloc_node mm/slub.c:3348 [inline]
__kmem_cache_alloc_node+0x204/0x2d0 mm/slub.c:3423
__do_kmalloc_node mm/slab_common.c:937 [inline]
__kmalloc+0xa4/0x1e0 mm/slab_common.c:951
kmalloc_array include/linux/slab.h:615 [inline]
blk_stat_alloc_callback+0x91/0x210 block/blk-stat.c:113
blk_mq_init_allocated_queue+0x178/0x1700 block/blk-mq.c:4362
blk_mq_init_queue_data block/blk-mq.c:4189 [inline]
blk_mq_init_queue+0xa6/0x120 block/blk-mq.c:4199
scsi_alloc_sdev+0x6a4/0xac0 drivers/scsi/scsi_scan.c:335
scsi_probe_and_add_lun+0x18f/0x3ce0 drivers/scsi/scsi_scan.c:1185
__scsi_scan_target+0x1ea/0xc20 drivers/scsi/scsi_scan.c:1721
page_owner free stack trace missing
Memory state around the buggy address:
ffff88810d70cf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88810d70cf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88810d70d000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88810d70d080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88810d70d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
general protection fault, probably for non-canonical address 0xec6d2accac84084d: 0000 [#1] PREEMPT SMP KASAN
KASAN: maybe wild-memory-access in range [0x6369766564204268-0x636976656420426f]
CPU: 1 PID: 1117 Comm: syz.5.200 Tainted: G B syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:kobj_child_ns_ops lib/kobject.c:1052 [inline]
RIP: 0010:kobj_ns_ops lib/kobject.c:1060 [inline]
RIP: 0010:kobject_namespace lib/kobject.c:30 [inline]
RIP: 0010:create_dir lib/kobject.c:63 [inline]
RIP: 0010:kobject_add_internal+0x58f/0xc20 lib/kobject.c:231
Code: 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 ff e8 c8 5d c9 fc 4d 8b 3f 4d 85 ff 0f 84 cc 00 00 00 49 83 c7 18 4c 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 ff e8 a2 5d c9 fc 49 8b 07 48 85 c0 0f
RSP: 0018:ffffc90003a1f8b8 EFLAGS: 00010206
RAX: 0c6d2eccac84084d RBX: ffff88810ddab800 RCX: ffffffff84ed9328
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff88810d70d028
RBP: ffffc90003a1f910 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000743f08 R12: dffffc0000000000
R13: 1ffff11021bb5705 R14: ffffffff8747f440 R15: 636976656420426b
FS: 00007f45fdcea6c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000556240fdf688 CR3: 0000000123fba000 CR4: 00000000003526a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
kobject_add_varg lib/kobject.c:366 [inline]
kobject_add+0x165/0x230 lib/kobject.c:418
class_dir_create_and_add drivers/base/core.c:3235 [inline]
get_device_parent+0x3a6/0x410 drivers/base/core.c:3290
device_add+0x308/0xec0 drivers/base/core.c:3619
device_create_groups_vargs drivers/base/core.c:4392 [inline]
device_create+0x26c/0x300 drivers/base/core.c:4434
create_function_device+0x60/0x70 drivers/usb/gadget/configfs.c:36
create_alsa_device drivers/usb/gadget/function/f_midi.c:1306 [inline]
f_midi_alloc_inst+0x1a8/0x380 drivers/usb/gadget/function/f_midi.c:1347
try_get_usb_function_instance drivers/usb/gadget/functions.c:28 [inline]
usb_get_function_instance+0xf3/0x310 drivers/usb/gadget/functions.c:44
function_make+0x118/0x360 drivers/usb/gadget/configfs.c:652
configfs_mkdir+0x518/0x9e0 fs/configfs/dir.c:1329
vfs_mkdir+0x39c/0x580 fs/namei.c:4113
do_mkdirat+0x174/0x4d0 fs/namei.c:4138
__do_sys_mkdirat fs/namei.c:4153 [inline]
__se_sys_mkdirat fs/namei.c:4151 [inline]
__x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4151
x64_sys_call+0x73d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:259
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: 0033:0x7f45fcd9e0d9
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:00007f45fdcea028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f45fd026090 RCX: 00007f45fcd9e0d9
RDX: 00000000000001ff RSI: 00002000000003c0 RDI: ffffffffffffff9c
RBP: 00007f45fce35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f45fd026128 R14: 00007f45fd026090 R15: 00007ffd8dc720f8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:kobj_child_ns_ops lib/kobject.c:1052 [inline]
RIP: 0010:kobj_ns_ops lib/kobject.c:1060 [inline]
RIP: 0010:kobject_namespace lib/kobject.c:30 [inline]
RIP: 0010:create_dir lib/kobject.c:63 [inline]
RIP: 0010:kobject_add_internal+0x58f/0xc20 lib/kobject.c:231
Code: 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 ff e8 c8 5d c9 fc 4d 8b 3f 4d 85 ff 0f 84 cc 00 00 00 49 83 c7 18 4c 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 ff e8 a2 5d c9 fc 49 8b 07 48 85 c0 0f
RSP: 0018:ffffc90003a1f8b8 EFLAGS: 00010206
RAX: 0c6d2eccac84084d RBX: ffff88810ddab800 RCX: ffffffff84ed9328
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff88810d70d028
RBP: ffffc90003a1f910 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000743f08 R12: dffffc0000000000
R13: 1ffff11021bb5705 R14: ffffffff8747f440 R15: 636976656420426b
FS: 00007f45fdcea6c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32723ffc CR3: 0000000123fba000 CR4: 00000000003526b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 48 c1 e8 03 shr $0x3,%rax
4: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1)
9: 74 08 je 0x13
b: 4c 89 ff mov %r15,%rdi
e: e8 c8 5d c9 fc call 0xfcc95ddb
13: 4d 8b 3f mov (%r15),%r15
16: 4d 85 ff test %r15,%r15
19: 0f 84 cc 00 00 00 je 0xeb
1f: 49 83 c7 18 add $0x18,%r15
23: 4c 89 f8 mov %r15,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 4c 89 ff mov %r15,%rdi
34: e8 a2 5d c9 fc call 0xfcc95ddb
39: 49 8b 07 mov (%r15),%rax
3c: 48 85 c0 test %rax,%rax
3f: 0f .byte 0xf
Struck through repros no longer work on HEAD.