================================================================== BUG: KASAN: slab-use-after-free in madvise_walk_vmas+0x661/0xae0 mm/madvise.c:1733 Read of size 8 at addr ffff888033895a08 by task syz.5.653/8298 CPU: 1 UID: 0 PID: 8298 Comm: syz.5.653 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description+0x55/0x1e0 mm/kasan/report.c:378 print_report+0x58/0x70 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 madvise_walk_vmas+0x661/0xae0 mm/madvise.c:1733 madvise_do_behavior+0x386/0x540 mm/madvise.c:1936 do_madvise+0x1fa/0x2e0 mm/madvise.c:2029 __do_sys_madvise mm/madvise.c:2038 [inline] __se_sys_madvise mm/madvise.c:2036 [inline] __x64_sys_madvise+0xa6/0xc0 mm/madvise.c:2036 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f13f8b9c819 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:00007f13f9adb028 EFLAGS: 00000246 ORIG_RAX: 000000000000001c RAX: ffffffffffffffda RBX: 00007f13f8e16090 RCX: 00007f13f8b9c819 RDX: 0000000000000019 RSI: 0000000008000000 RDI: 0000200000000000 RBP: 00007f13f8c32c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f13f8e16128 R14: 00007f13f8e16090 R15: 00007ffc7f081a78 Allocated by task 6536: 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:4569 [inline] slab_alloc_node mm/slub.c:4898 [inline] kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4905 vm_area_dup+0x2b/0x680 mm/vma_init.c:123 dup_mmap+0x8b1/0x1d90 mm/mmap.c:1786 dup_mm kernel/fork.c:1533 [inline] copy_mm+0x13b/0x4a0 kernel/fork.c:1585 copy_process+0x1efd/0x4430 kernel/fork.c:2260 kernel_clone+0x26d/0x8e0 kernel/fork.c:2709 __do_sys_clone kernel/fork.c:2850 [inline] __se_sys_clone kernel/fork.c:2834 [inline] __x64_sys_clone+0x1b6/0x230 kernel/fork.c:2834 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 8279: 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:2689 [inline] slab_free_after_rcu_debug+0x12a/0x220 mm/slub.c:6304 rcu_do_batch kernel/rcu/tree.c:2617 [inline] rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869 handle_softirqs+0x22a/0x840 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0xca/0x220 kernel/softirq.c:735 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061 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 slab_free_hook mm/slub.c:2650 [inline] slab_free mm/slub.c:6242 [inline] kmem_cache_free+0x44f/0x650 mm/slub.c:6369 remove_vma mm/vma.c:473 [inline] vms_complete_munmap_vmas+0x929/0xc60 mm/vma.c:1415 do_vmi_align_munmap+0x3b7/0x4b0 mm/vma.c:1660 do_vmi_munmap+0x252/0x2d0 mm/vma.c:1708 do_munmap+0xf9/0x170 mm/mmap.c:1067 mremap_to+0x353/0x880 mm/mremap.c:1450 do_mremap mm/mremap.c:2001 [inline] __do_sys_mremap mm/mremap.c:2057 [inline] __se_sys_mremap+0xe6d/0x11d0 mm/mremap.c:2025 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff888033895a00 which belongs to the cache vm_area_struct of size 256 The buggy address is located 8 bytes inside of freed 256-byte region [ffff888033895a00, ffff888033895b00) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x33895 memcg:ffff88807675a481 flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000000 ffff888140410500 dead000000000100 dead000000000122 raw: 0000000000000000 00000008000c000c 00000000f5000000 ffff88807675a481 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 5499, tgid 5499 (run-parts), ts 51900734155, free_ts 50080249486 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x231/0x280 mm/page_alloc.c:1858 prep_new_page mm/page_alloc.c:1866 [inline] get_page_from_freelist+0x24ba/0x2540 mm/page_alloc.c:3946 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226 alloc_slab_page mm/slub.c:3278 [inline] allocate_slab+0x77/0x660 mm/slub.c:3467 new_slab mm/slub.c:3525 [inline] refill_objects+0x339/0x3d0 mm/slub.c:7247 refill_sheaf mm/slub.c:2816 [inline] __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4651 alloc_from_pcs mm/slub.c:4749 [inline] slab_alloc_node mm/slub.c:4883 [inline] kmem_cache_alloc_noprof+0x37d/0x650 mm/slub.c:4905 vm_area_alloc+0x24/0x140 mm/vma_init.c:32 __mmap_new_vma mm/vma.c:2606 [inline] __mmap_region mm/vma.c:2836 [inline] mmap_region+0x11be/0x2370 mm/vma.c:2914 do_mmap+0xc39/0x10c0 mm/mmap.c:560 vm_mmap_pgoff+0x2c9/0x4f0 mm/util.c:581 ksys_mmap_pgoff+0x51e/0x760 mm/mmap.c:606 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f page last free pid 5213 tgid 5213 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1402 [inline] __free_frozen_pages+0xbc7/0xd30 mm/page_alloc.c:2943 __slab_free+0x274/0x2c0 mm/slub.c:5605 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4569 [inline] slab_alloc_node mm/slub.c:4898 [inline] kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4905 alloc_filename fs/namei.c:142 [inline] do_getname+0x2e/0x250 fs/namei.c:182 getname_flags fs/namei.c:225 [inline] getname include/linux/fs.h:2520 [inline] class_filename_constructor include/linux/fs.h:2547 [inline] __do_sys_symlink fs/namei.c:5693 [inline] __se_sys_symlink+0x2b/0x2b0 fs/namei.c:5691 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff888033895900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888033895980: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc >ffff888033895a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888033895a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888033895b00: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ==================================================================