do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 ================================================================== BUG: KASAN: use-after-free in qfq_reset_qdisc+0xcc/0x208 net/sched/sch_qfq.c:1486 Read of size 8 at addr ffff0000d80cc750 by task syz.0.17/4510 CPU: 1 PID: 4510 Comm: syz.0.17 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025 Call trace: dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106 print_address_description+0x88/0x218 mm/kasan/report.c:316 print_report+0x50/0x68 mm/kasan/report.c:420 kasan_report+0xa8/0x100 mm/kasan/report.c:524 __asan_report_load8_noabort+0x2c/0x38 mm/kasan/report_generic.c:351 qfq_reset_qdisc+0xcc/0x208 net/sched/sch_qfq.c:1486 qdisc_reset+0x134/0x604 net/sched/sch_generic.c:1038 __qdisc_destroy+0x100/0x500 net/sched/sch_generic.c:1076 qdisc_put net/sched/sch_generic.c:1107 [inline] dev_shutdown+0x35c/0x47c net/sched/sch_generic.c:1495 unregister_netdevice_many+0x944/0x1740 net/core/dev.c:10981 unregister_netdevice_queue+0x2ac/0x2f8 net/core/dev.c:10921 unregister_netdevice include/linux/netdevice.h:3075 [inline] __tun_detach+0xb04/0x122c drivers/net/tun.c:685 tun_detach drivers/net/tun.c:701 [inline] tun_chr_close+0x118/0x1f8 drivers/net/tun.c:3492 __fput+0x1bc/0x7c0 fs/file_table.c:320 ____fput+0x20/0x30 fs/file_table.c:348 task_work_run+0x1ec/0x270 kernel/task_work.c:203 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] do_notify_resume+0x2038/0x2b28 arch/arm64/kernel/signal.c:1137 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline] el0_svc+0x98/0x138 arch/arm64/kernel/entry-common.c:638 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 Allocated by task 4510: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4c/0x80 mm/kasan/common.c:52 kasan_save_alloc_info+0x28/0x34 mm/kasan/generic.c:505 ____kasan_kmalloc mm/kasan/common.c:374 [inline] __kasan_kmalloc+0xa0/0xb8 mm/kasan/common.c:383 kasan_kmalloc include/linux/kasan.h:211 [inline] kmalloc_trace+0x7c/0x94 mm/slab_common.c:1031 kmalloc include/linux/slab.h:563 [inline] kzalloc include/linux/slab.h:699 [inline] qfq_change_class+0x358/0xa68 net/sched/sch_qfq.c:483 tc_ctl_tclass+0x840/0xb34 net/sched/sch_api.c:2202 rtnetlink_rcv_msg+0x734/0xce4 net/core/rtnetlink.c:6150 netlink_rcv_skb+0x208/0x3c4 net/netlink/af_netlink.c:2511 rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6168 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x60c/0x824 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x6e8/0x9b0 net/netlink/af_netlink.c:1872 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] ____sys_sendmsg+0x5b8/0x918 net/socket.c:2519 ___sys_sendmsg net/socket.c:2573 [inline] __sys_sendmsg+0x25c/0x320 net/socket.c:2602 __do_sys_sendmsg net/socket.c:2611 [inline] __se_sys_sendmsg net/socket.c:2609 [inline] __arm64_sys_sendmsg+0x80/0x94 net/socket.c:2609 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 Freed by task 4510: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4c/0x80 mm/kasan/common.c:52 kasan_save_free_info+0x3c/0x60 mm/kasan/generic.c:516 ____kasan_slab_free+0x148/0x1b0 mm/kasan/common.c:236 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:244 kasan_slab_free include/linux/kasan.h:177 [inline] slab_free_hook mm/slub.c:1729 [inline] slab_free_freelist_hook+0x16c/0x1ec mm/slub.c:1755 slab_free mm/slub.c:3687 [inline] __kmem_cache_free+0xc0/0x224 mm/slub.c:3700 kfree+0xd0/0x1ac mm/slab_common.c:988 qfq_change_class+0x818/0xa68 net/sched/sch_qfq.c:537 tc_ctl_tclass+0x840/0xb34 net/sched/sch_api.c:2202 rtnetlink_rcv_msg+0x734/0xce4 net/core/rtnetlink.c:6150 netlink_rcv_skb+0x208/0x3c4 net/netlink/af_netlink.c:2511 rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6168 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x60c/0x824 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x6e8/0x9b0 net/netlink/af_netlink.c:1872 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] ____sys_sendmsg+0x5b8/0x918 net/socket.c:2519 ___sys_sendmsg net/socket.c:2573 [inline] __sys_sendmsg+0x25c/0x320 net/socket.c:2602 __do_sys_sendmsg net/socket.c:2611 [inline] __se_sys_sendmsg net/socket.c:2609 [inline] __arm64_sys_sendmsg+0x80/0x94 net/socket.c:2609 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 Last potentially related work creation: kasan_save_stack+0x40/0x70 mm/kasan/common.c:45 __kasan_record_aux_stack+0xc0/0xdc mm/kasan/generic.c:486 kasan_record_aux_stack_noalloc+0x14/0x20 mm/kasan/generic.c:496 kvfree_call_rcu+0xb4/0x6f0 kernel/rcu/tree.c:3405 kernfs_unlink_open_file+0x37c/0x42c fs/kernfs/file.c:653 kernfs_fop_release+0x128/0x190 fs/kernfs/file.c:825 __fput+0x1bc/0x7c0 fs/file_table.c:320 ____fput+0x20/0x30 fs/file_table.c:348 task_work_run+0x1ec/0x270 kernel/task_work.c:203 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] do_notify_resume+0x2038/0x2b28 arch/arm64/kernel/signal.c:1137 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline] el0_svc+0x98/0x138 arch/arm64/kernel/entry-common.c:638 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 The buggy address belongs to the object at ffff0000d80cc700 which belongs to the cache kmalloc-128 of size 128 The buggy address is located 80 bytes inside of 128-byte region [ffff0000d80cc700, ffff0000d80cc780) The buggy address belongs to the physical page: page:00000000cb61cffd refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1180cc flags: 0x5ffc00000000200(slab|node=0|zone=2|lastcpupid=0x7ff) raw: 05ffc00000000200 fffffc0003491440 dead000000000003 ffff0000c0002300 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000d80cc600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000d80cc680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff0000d80cc700: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000d80cc780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000d80cc800: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== Unable to handle kernel paging request at virtual address e0d84074e000023c KASAN: maybe wild-memory-access in range [0x06c603a7000011e0-0x06c603a7000011e7] Mem abort info: ESR = 0x0000000096000004 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x04: level 0 translation fault Data abort info: ISV = 0, ISS = 0x00000004 CM = 0, WnR = 0 [e0d84074e000023c] address between user and kernel address ranges Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP Modules linked in: CPU: 1 PID: 4510 Comm: syz.0.17 Tainted: G B syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025 pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--) pc : qfq_reset_qdisc+0xbc/0x208 net/sched/sch_qfq.c:1486 lr : qfq_reset_qdisc+0x158/0x208 net/sched/sch_qfq.c:1485 sp : ffff8000211f75a0 x29: ffff8000211f75b0 x28: 0000000000000000 x27: 1fffe0001b27f05a x26: 00d8c074e000023c x25: dfff800000000000 x24: 0000000000000000 x23: 06c603a7000011e6 x22: 06c603a700001196 x21: ffff0000d93f82d0 x20: ffff0000d93f82d8 x19: ffff0000d93f8000 x18: ffff800011a5bd40 x17: 0000000000000000 x16: ffff800008042d90 x15: 0000000000000000 x14: 00000000ffffffff x13: 0000000000000001 x12: 0000000000ff0100 x11: ff0080000ff41dac x10: 0000000000000000 x9 : ffff80000ff41dac x8 : ffff0000c38d1bc0 x7 : 0000000000000001 x6 : 0000000000000001 x5 : ffff8000211f6f78 x4 : ffff800015134e00 x3 : ffff80000ff41d98 x2 : 0000000000000000 x1 : 0000000000000008 x0 : 0000000000000000 Call trace: qfq_reset_qdisc+0xbc/0x208 net/sched/sch_qfq.c:1486 qdisc_reset+0x134/0x604 net/sched/sch_generic.c:1038 __qdisc_destroy+0x100/0x500 net/sched/sch_generic.c:1076 qdisc_put net/sched/sch_generic.c:1107 [inline] dev_shutdown+0x35c/0x47c net/sched/sch_generic.c:1495 unregister_netdevice_many+0x944/0x1740 net/core/dev.c:10981 unregister_netdevice_queue+0x2ac/0x2f8 net/core/dev.c:10921 unregister_netdevice include/linux/netdevice.h:3075 [inline] __tun_detach+0xb04/0x122c drivers/net/tun.c:685 tun_detach drivers/net/tun.c:701 [inline] tun_chr_close+0x118/0x1f8 drivers/net/tun.c:3492 __fput+0x1bc/0x7c0 fs/file_table.c:320 ____fput+0x20/0x30 fs/file_table.c:348 task_work_run+0x1ec/0x270 kernel/task_work.c:203 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] do_notify_resume+0x2038/0x2b28 arch/arm64/kernel/signal.c:1137 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline] el0_svc+0x98/0x138 arch/arm64/kernel/entry-common.c:638 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 Code: d1002116 b4000656 910142d7 d343fefa (38796b48) ---[ end trace 0000000000000000 ]--- ---------------- Code disassembly (best guess): 0: d1002116 sub x22, x8, #0x8 4: b4000656 cbz x22, 0xcc 8: 910142d7 add x23, x22, #0x50 c: d343fefa lsr x26, x23, #3 * 10: 38796b48 ldrb w8, [x26, x25] <-- trapping instruction