==================================================================
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 ffff888026f531c0 by task syz.0.189/6507

CPU: 1 UID: 0 PID: 6507 Comm: syz.0.189 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
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:2949
 seq_vprintf fs/seq_file.c:392 [inline]
 seq_printf+0x1a4/0x250 fs/seq_file.c:407
 irq_seq_show+0x390/0x8b0 kernel/irq/proc.c:601
 seq_read_iter+0xbce/0x1270 fs/seq_file.c:273
 proc_reg_read_iter+0x220/0x310 fs/proc/inode.c:299
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x82e/0xb40 fs/read_write.c:574
 ksys_read+0x12a/0x250 fs/read_write.c:716
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f99fcf9e159
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:00007f99fde94028 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f99fd226090 RCX: 00007f99fcf9e159
RDX: 00000000000003e8 RSI: 0000200000000400 RDI: 0000000000000005
RBP: 00007f99fd03506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f99fd226128 R14: 00007f99fd226090 R15: 00007fff46b55e48
 </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:409 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:426
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5414 [inline]
 __kmalloc_node_track_caller_noprof+0x33d/0x870 mm/slub.c:5545
 kvasprintf+0xbc/0x150 lib/kasprintf.c:25
 kasprintf+0xc7/0x100 lib/kasprintf.c:59
 serial_core_add_one_port drivers/tty/serial/serial_core.c:3106 [inline]
 serial_core_register_port+0x46b/0x1660 drivers/tty/serial/serial_core.c:3353
 serial8250_register_8250_port+0x16c7/0x2440 drivers/tty/serial/8250/8250_core.c:877
 serial_pnp_probe+0x443/0x950 drivers/tty/serial/8250/8250_pnp.c:480
 pnp_device_probe+0x2b3/0x4a0 drivers/pnp/driver.c:111
 call_driver_probe drivers/base/dd.c:628 [inline]
 really_probe+0x241/0xa60 drivers/base/dd.c:706
 __driver_probe_device+0x210/0x460 drivers/base/dd.c:868
 driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
 __driver_attach+0x21f/0x5b0 drivers/base/dd.c:1292
 bus_for_each_dev+0x13e/0x1d0 drivers/base/bus.c:383
 bus_add_driver+0x305/0x5b0 drivers/base/bus.c:763
 driver_register+0x1e2/0x360 drivers/base/driver.c:174
 serial8250_init+0xcc/0x1c0 drivers/tty/serial/8250/8250_platform.c:318
 do_one_initcall+0x11c/0x6f0 init/main.c:1362
 do_initcall_level init/main.c:1424 [inline]
 do_initcalls init/main.c:1440 [inline]
 do_basic_setup init/main.c:1460 [inline]
 kernel_init_freeable+0x6ea/0x7b0 init/main.c:1675
 kernel_init+0x21/0x1e0 init/main.c:1565
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 6310:
 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:264 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:296
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2748 [inline]
 slab_free mm/slub.c:6508 [inline]
 kfree+0x22b/0x6d0 mm/slub.c:6801
 serial_core_remove_one_port drivers/tty/serial/serial_core.c:3222 [inline]
 serial_core_unregister_port+0x4b9/0x960 drivers/tty/serial/serial_core.c:3383
 serial8250_unregister_port+0x1db/0x890 drivers/tty/serial/8250/8250_core.c:932
 pnp_device_remove+0x7f/0x250 drivers/pnp/driver.c:133
 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+0x6af/0x1050 fs/read_write.c:687
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888026f531c0
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 0 bytes inside of
 freed 8-byte region [ffff888026f531c0, ffff888026f531c8)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x26f53
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801c031500 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000800080 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 4243292340
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1871
 prep_new_page mm/page_alloc.c:1879 [inline]
 get_page_from_freelist+0x110d/0x35d0 mm/page_alloc.c:3943
 __alloc_frozen_pages_noprof+0x2eb/0x3300 mm/page_alloc.c:5436
 alloc_slab_page mm/slub.c:3347 [inline]
 allocate_slab mm/slub.c:3462 [inline]
 new_slab+0xa9/0x6e0 mm/slub.c:3513
 refill_objects+0xe3/0x410 mm/slub.c:7417
 refill_sheaf mm/slub.c:2885 [inline]
 __pcs_replace_empty_main+0x35e/0x650 mm/slub.c:4774
 alloc_from_pcs mm/slub.c:4850 [inline]
 slab_alloc_node mm/slub.c:4984 [inline]
 __do_kmalloc_node mm/slub.c:5413 [inline]
 __kmalloc_node_track_caller_noprof+0x6a8/0x870 mm/slub.c:5545
 __kmemdup_nul mm/util.c:64 [inline]
 kstrdup+0x51/0xe0 mm/util.c:84
 kstrdup_const+0x63/0x80 mm/util.c:104
 __kernfs_new_node+0x9b/0xa10 fs/kernfs/dir.c:661
 kernfs_new_node fs/kernfs/dir.c:751 [inline]
 kernfs_create_dir_ns+0xa6/0x2b0 fs/kernfs/dir.c:1120
 sysfs_create_dir_ns+0x13a/0x2b0 fs/sysfs/dir.c:59
 create_dir lib/kobject.c:73 [inline]
 kobject_add_internal+0x2c8/0x930 lib/kobject.c:240
 kobject_add_varg lib/kobject.c:374 [inline]
 kobject_add+0x16a/0x1e0 lib/kobject.c:426
 device_add+0x294/0x1970 drivers/base/core.c:3699
 tty_register_device_attr+0x388/0x7f0 drivers/tty/tty_io.c:3236
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888026f53080: 06 fc fc fc 06 fc fc fc 06 fc fc fc 06 fc fc fc
 ffff888026f53100: 05 fc fc fc 05 fc fc fc 05 fc fc fc 05 fc fc fc
>ffff888026f53180: 05 fc fc fc 05 fc fc fc fa fc fc fc 05 fc fc fc
                                           ^
 ffff888026f53200: fa fc fc fc 00 fc fc fc 05 fc fc fc 00 fc fc fc
 ffff888026f53280: fa fc fc fc fa fc fc fc 04 fc fc fc 00 fc fc fc
==================================================================