================================================================== BUG: KASAN: slab-use-after-free in qfq_reset_qdisc+0x323/0x420 net/sched/sch_qfq.c:1484 Read of size 8 at addr ffff888036715250 by task syz.0.2076/13811 CPU: 1 UID: 0 PID: 13811 Comm: syz.0.2076 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xcd/0x630 mm/kasan/report.c:482 kasan_report+0xe0/0x110 mm/kasan/report.c:595 qfq_reset_qdisc+0x323/0x420 net/sched/sch_qfq.c:1484 qdisc_reset+0xe0/0x630 net/sched/sch_generic.c:1034 __qdisc_destroy+0xd3/0x4a0 net/sched/sch_generic.c:1073 qdisc_put+0xab/0xe0 net/sched/sch_generic.c:1105 dev_shutdown+0x1d0/0x430 net/sched/sch_generic.c:1493 unregister_netdevice_many_notify+0xb37/0x2590 net/core/dev.c:12369 unregister_netdevice_many net/core/dev.c:12444 [inline] unregister_netdevice_queue net/core/dev.c:12258 [inline] unregister_netdevice_queue+0x305/0x3c0 net/core/dev.c:12248 unregister_netdevice include/linux/netdevice.h:3405 [inline] __tun_detach+0x119c/0x1490 drivers/net/tun.c:621 tun_detach drivers/net/tun.c:637 [inline] tun_chr_close+0xc2/0x230 drivers/net/tun.c:3436 __fput+0x402/0xb70 fs/file_table.c:468 task_work_run+0x150/0x240 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:44 [inline] exit_to_user_mode_loop+0xfb/0x540 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x4ee/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fc121d8f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffef5419478 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007fc121fe7da0 RCX: 00007fc121d8f749 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007fc121fe7da0 R08: 0000000000000000 R09: 0000000ff541976f R10: 000000000003fd5c R11: 0000000000000246 R12: 000000000009d866 R13: 00007fc121fe6090 R14: ffffffffffffffff R15: 00007ffef5419590 Allocated by task 13812: kasan_save_stack+0x33/0x60 mm/kasan/common.c:56 kasan_save_track+0x14/0x30 mm/kasan/common.c:77 poison_kmalloc_redzone mm/kasan/common.c:397 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:414 kmalloc_noprof include/linux/slab.h:957 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] qfq_change_class+0x2ba/0x1da0 net/sched/sch_qfq.c:479 __tc_ctl_tclass net/sched/sch_api.c:2279 [inline] tc_ctl_tclass+0x59d/0x16c0 net/sched/sch_api.c:2309 rtnetlink_rcv_msg+0x3c9/0xe90 net/core/rtnetlink.c:6967 netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2550 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0xa5d/0xc30 net/socket.c:2592 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2646 __sys_sendmsg+0x16d/0x220 net/socket.c:2678 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 13812: kasan_save_stack+0x33/0x60 mm/kasan/common.c:56 kasan_save_track+0x14/0x30 mm/kasan/common.c:77 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:252 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:284 kasan_slab_free include/linux/kasan.h:234 [inline] slab_free_hook mm/slub.c:2540 [inline] slab_free mm/slub.c:6663 [inline] kfree+0x2f8/0x6e0 mm/slub.c:6871 qfq_change_class+0x1576/0x1da0 net/sched/sch_qfq.c:533 __tc_ctl_tclass net/sched/sch_api.c:2279 [inline] tc_ctl_tclass+0x59d/0x16c0 net/sched/sch_api.c:2309 rtnetlink_rcv_msg+0x3c9/0xe90 net/core/rtnetlink.c:6967 netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2550 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0xa5d/0xc30 net/socket.c:2592 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2646 __sys_sendmsg+0x16d/0x220 net/socket.c:2678 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff888036715200 which belongs to the cache kmalloc-128 of size 128 The buggy address is located 80 bytes inside of freed 128-byte region [ffff888036715200, ffff888036715280) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888036715000 pfn:0x36715 flags: 0xfff00000000200(workingset|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000200 ffff88813ff26a00 ffffea0001efc510 ffffea0001563550 raw: ffff888036715000 000000000010000e 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 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5189, tgid 5189 (udevd), ts 36404644860, free_ts 36374984199 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1af/0x220 mm/page_alloc.c:1846 prep_new_page mm/page_alloc.c:1854 [inline] get_page_from_freelist+0xd0b/0x31a0 mm/page_alloc.c:3915 __alloc_frozen_pages_noprof+0x25f/0x2430 mm/page_alloc.c:5210 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2486 alloc_slab_page mm/slub.c:3075 [inline] allocate_slab mm/slub.c:3248 [inline] new_slab+0x2c3/0x430 mm/slub.c:3302 ___slab_alloc+0xe18/0x1c90 mm/slub.c:4651 __slab_alloc.constprop.0+0x63/0x110 mm/slub.c:4774 __slab_alloc_node mm/slub.c:4850 [inline] slab_alloc_node mm/slub.c:5246 [inline] __kmalloc_cache_noprof+0x485/0x800 mm/slub.c:5766 kmalloc_noprof include/linux/slab.h:957 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] kernfs_get_open_node fs/kernfs/file.c:543 [inline] kernfs_fop_open+0xa3a/0xda0 fs/kernfs/file.c:718 do_dentry_open+0x748/0x1590 fs/open.c:962 vfs_open+0x82/0x3f0 fs/open.c:1094 do_open fs/namei.c:4628 [inline] path_openat+0x2078/0x3140 fs/namei.c:4787 do_filp_open+0x20b/0x470 fs/namei.c:4814 do_sys_openat2+0x11f/0x280 fs/open.c:1430 do_sys_open fs/open.c:1436 [inline] __do_sys_openat fs/open.c:1452 [inline] __se_sys_openat fs/open.c:1447 [inline] __x64_sys_openat+0x174/0x210 fs/open.c:1447 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94 page last free pid 15 tgid 15 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1395 [inline] __free_frozen_pages+0x7df/0x1170 mm/page_alloc.c:2943 rcu_do_batch kernel/rcu/tree.c:2605 [inline] rcu_core+0x79c/0x15f0 kernel/rcu/tree.c:2857 handle_softirqs+0x219/0x950 kernel/softirq.c:622 run_ksoftirqd kernel/softirq.c:1063 [inline] run_ksoftirqd+0x3a/0x60 kernel/softirq.c:1055 smpboot_thread_fn+0x3f7/0xae0 kernel/smpboot.c:160 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 Memory state around the buggy address: ffff888036715100: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888036715180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888036715200: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888036715280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888036715300: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc ==================================================================