================================================================== BUG: KASAN: slab-use-after-free in __list_add_valid_or_report+0x4e/0x130 lib/list_debug.c:29 Read of size 8 at addr ffff8880747f4440 by task syz.5.9489/1211 CPU: 0 UID: 0 PID: 1211 Comm: syz.5.9489 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_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xca/0x240 mm/kasan/report.c:482 kasan_report+0x118/0x150 mm/kasan/report.c:595 __list_add_valid_or_report+0x4e/0x130 lib/list_debug.c:29 __list_add_valid include/linux/list.h:96 [inline] __list_add include/linux/list.h:158 [inline] list_add include/linux/list.h:177 [inline] clone_mnt+0x447/0x9a0 fs/namespace.c:1286 copy_tree+0xde/0x930 fs/namespace.c:2170 copy_mnt_ns+0x11f/0x7c0 fs/namespace.c:4249 create_new_namespaces+0xcf/0x6a0 kernel/nsproxy.c:98 unshare_nsproxy_namespaces+0x11c/0x170 kernel/nsproxy.c:226 ksys_unshare+0x4c8/0x8c0 kernel/fork.c:3168 __do_sys_unshare kernel/fork.c:3239 [inline] __se_sys_unshare kernel/fork.c:3237 [inline] __x64_sys_unshare+0x38/0x50 kernel/fork.c:3237 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f9df0f8f749 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:00007f9def1f6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000110 RAX: ffffffffffffffda RBX: 00007f9df11e5fa0 RCX: 00007f9df0f8f749 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000002a060600 RBP: 00007f9df1013f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f9df11e6038 R14: 00007f9df11e5fa0 R15: 00007ffcc574ada8 Allocated by task 30875: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:5187 [inline] slab_alloc_node mm/slub.c:5500 [inline] kmem_cache_alloc_noprof+0x37d/0x710 mm/slub.c:5507 alloc_vfsmnt+0x23/0x420 fs/namespace.c:298 clone_mnt+0x4b/0x9a0 fs/namespace.c:1257 open_new_namespace fs/namespace.c:3110 [inline] vfs_open_tree+0x4e8/0xf50 fs/namespace.c:3220 __do_sys_open_tree fs/namespace.c:3230 [inline] __se_sys_open_tree fs/namespace.c:3228 [inline] __x64_sys_open_tree+0x96/0x110 fs/namespace.c:3228 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 0: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2768 [inline] slab_free mm/slub.c:6911 [inline] kmem_cache_free+0x195/0x630 mm/slub.c:7022 rcu_do_batch kernel/rcu/tree.c:2617 [inline] rcu_core+0x7bd/0x1060 kernel/rcu/tree.c:2869 handle_softirqs+0x22b/0x7c0 kernel/softirq.c:626 __do_softirq kernel/softirq.c:660 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0x60/0x150 kernel/softirq.c:727 irq_exit_rcu+0x9/0x30 kernel/softirq.c:743 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 Last potentially related work creation: kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556 __call_rcu_common kernel/rcu/tree.c:3131 [inline] call_rcu+0xee/0x890 kernel/rcu/tree.c:3251 task_work_run+0x1d4/0x260 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+0xef/0x4e0 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+0x2c1/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f Second to last potentially related work creation: kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556 task_work_add+0xb1/0x440 kernel/task_work.c:70 mntput_no_expire_slowpath+0x710/0xbe0 fs/namespace.c:1390 open_new_namespace fs/namespace.c:3175 [inline] vfs_open_tree+0xd76/0xf50 fs/namespace.c:3220 __do_sys_open_tree fs/namespace.c:3230 [inline] __se_sys_open_tree fs/namespace.c:3228 [inline] __x64_sys_open_tree+0x96/0x110 fs/namespace.c:3228 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff8880747f4380 which belongs to the cache mnt_cache of size 352 The buggy address is located 192 bytes inside of freed 352-byte region [ffff8880747f4380, ffff8880747f44e0) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8880747f4700 pfn:0x747f4 head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:ffff8880603d6f01 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88801c2c1c80 ffffea0000e92100 dead000000000004 raw: ffff8880747f4700 0000000880120006 00000000f5000000 ffff8880603d6f01 head: 00fff00000000040 ffff88801c2c1c80 ffffea0000e92100 dead000000000004 head: ffff8880747f4700 0000000880120006 00000000f5000000 ffff8880603d6f01 head: 00fff00000000001 ffffea0001d1fd01 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5822, tgid 5822 (syz-executor), ts 86866752041, free_ts 31783688525 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x23d/0x2a0 mm/page_alloc.c:1887 prep_new_page mm/page_alloc.c:1895 [inline] get_page_from_freelist+0x23a5/0x2440 mm/page_alloc.c:3948 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5236 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486 alloc_slab_page mm/slub.c:3303 [inline] allocate_slab+0x87/0x670 mm/slub.c:3478 new_slab mm/slub.c:3536 [inline] ___slab_alloc+0xdb6/0x17b0 mm/slub.c:4890 __slab_alloc+0x65/0x100 mm/slub.c:5013 __slab_alloc_node mm/slub.c:5089 [inline] slab_alloc_node mm/slub.c:5488 [inline] kmem_cache_alloc_noprof+0x40f/0x710 mm/slub.c:5507 alloc_vfsmnt+0x23/0x420 fs/namespace.c:298 clone_mnt+0x4b/0x9a0 fs/namespace.c:1257 copy_tree+0x3d4/0x930 fs/namespace.c:2205 copy_mnt_ns+0x11f/0x7c0 fs/namespace.c:4249 create_new_namespaces+0xcf/0x6a0 kernel/nsproxy.c:98 unshare_nsproxy_namespaces+0x11c/0x170 kernel/nsproxy.c:226 ksys_unshare+0x4c8/0x8c0 kernel/fork.c:3168 __do_sys_unshare kernel/fork.c:3239 [inline] __se_sys_unshare kernel/fork.c:3237 [inline] __x64_sys_unshare+0x38/0x50 kernel/fork.c:3237 page last free pid 1 tgid 1 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1436 [inline] __free_frozen_pages+0xb99/0xd10 mm/page_alloc.c:2976 __free_pages mm/page_alloc.c:5355 [inline] free_contig_range+0x1bd/0x490 mm/page_alloc.c:7283 destroy_args+0x69/0x660 mm/debug_vm_pgtable.c:983 debug_vm_pgtable+0x38f/0x3a0 mm/debug_vm_pgtable.c:1372 do_one_initcall+0x1f1/0x800 init/main.c:1382 do_initcall_level+0x104/0x190 init/main.c:1444 do_initcalls+0x59/0xa0 init/main.c:1460 kernel_init_freeable+0x2a7/0x3e0 init/main.c:1692 kernel_init+0x1d/0x1d0 init/main.c:1582 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Memory state around the buggy address: ffff8880747f4300: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc ffff8880747f4380: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880747f4400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880747f4480: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff8880747f4500: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb 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