================================================================== 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 ffff8880270f8800 by task syz.4.2181/14636 CPU: 1 UID: 0 PID: 14636 Comm: syz.4.2181 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: __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 traverse.part.0.constprop.0+0x107/0x650 fs/seq_file.c:112 traverse fs/seq_file.c:99 [inline] seq_lseek+0x2fb/0x430 fs/seq_file.c:324 proc_reg_llseek+0x208/0x2f0 fs/proc/inode.c:283 vfs_llseek fs/read_write.c:391 [inline] ksys_lseek+0xf3/0x1b0 fs/read_write.c:404 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: 0033:0x7fbc4439e199 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:00007fbc452e6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000008 RAX: ffffffffffffffda RBX: 00007fbc44626090 RCX: 00007fbc4439e199 RDX: 0000000000000000 RSI: 0000002000000008 RDI: 0000000000000007 RBP: 00007fbc444358e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fbc44626128 R14: 00007fbc44626090 R15: 00007ffe67bc5d48 Allocated by task 12334: 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 __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_init_and_add+0x121/0x180 lib/kobject.c:457 rx_queue_add_kobject net/core/net-sysfs.c:1239 [inline] net_rx_queue_update_kobjects+0x37e/0x760 net/core/net-sysfs.c:1301 register_queue_kobjects net/core/net-sysfs.c:2093 [inline] netdev_register_kobject+0x2c6/0x410 net/core/net-sysfs.c:2344 register_netdevice+0x15b6/0x25a0 net/core/dev.c:11546 wg_newlink+0x3af/0x7a0 drivers/net/wireguard/device.c:372 rtnl_newlink_create net/core/rtnetlink.c:3974 [inline] __rtnl_newlink net/core/rtnetlink.c:4103 [inline] rtnl_newlink+0x1697/0x2620 net/core/rtnetlink.c:4220 rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:7137 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2575 netlink_unicast_kernel net/netlink/af_netlink.c:1338 [inline] netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1364 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1919 sock_sendmsg_nosec net/socket.c:800 [inline] __sock_sendmsg net/socket.c:815 [inline] __sys_sendto+0x48b/0x4e0 net/socket.c:2281 __do_sys_sendto net/socket.c:2288 [inline] __se_sys_sendto net/socket.c:2284 [inline] __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2284 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 Freed by task 24: 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:6509 [inline] kfree+0x22b/0x6d0 mm/slub.c:6802 kfree_const+0x5a/0x70 mm/util.c:46 kernfs_free_rcu+0x3d/0x100 fs/kernfs/dir.c:571 rcu_do_batch kernel/rcu/tree.c:2650 [inline] rcu_core+0x5f0/0x1260 kernel/rcu/tree.c:2919 handle_softirqs+0x1e6/0x9d0 kernel/softirq.c:645 run_ksoftirqd kernel/softirq.c:1099 [inline] run_ksoftirqd+0x38/0x60 kernel/softirq.c:1091 smpboot_thread_fn+0x3d3/0xab0 kernel/smpboot.c:160 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 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 ffff8880270f8800 which belongs to the cache kmalloc-8 of size 8 The buggy address is located 0 bytes inside of freed 8-byte region [ffff8880270f8800, ffff8880270f8808) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8880270f8840 pfn:0x270f8 flags: 0xfff00000000200(workingset|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000200 ffff88801c031500 ffffea000270e650 ffffea0000ad23d0 raw: ffff8880270f8840 000000000080007b 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 4039444192 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:7418 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+0x117/0x150 fs/kernfs/dir.c:751 kernfs_create_link+0xcc/0x240 fs/kernfs/symlink.c:39 sysfs_do_create_link_sd+0x90/0x140 fs/sysfs/symlink.c:44 sysfs_do_create_link fs/sysfs/symlink.c:80 [inline] sysfs_create_link+0x61/0xc0 fs/sysfs/symlink.c:92 device_create_sys_dev_entry drivers/base/core.c:3587 [inline] device_add+0xb62/0x1970 drivers/base/core.c:3731 tty_register_device_attr+0x388/0x810 drivers/tty/tty_io.c:3254 page_owner free stack trace missing Memory state around the buggy address: ffff8880270f8700: 05 fc fc fc 05 fc fc fc 05 fc fc fc 00 fc fc fc ffff8880270f8780: 05 fc fc fc 00 fc fc fc 05 fc fc fc 05 fc fc fc >ffff8880270f8800: fa fc fc fc 00 fc fc fc fa fc fc fc 00 fc fc fc ^ ffff8880270f8880: fa fc fc fc 00 fc fc fc fa fc fc fc fa fc fc fc ffff8880270f8900: 04 fc fc fc 00 fc fc fc 00 fc fc fc 06 fc fc fc ==================================================================