================================================================== BUG: KASAN: use-after-free in xattr_find_entry+0x1a5/0x280 fs/ext4/xattr.c:334 Read of size 4 at addr ffff888037dab004 by task syz.5.1969/14390 CPU: 1 UID: 49663 PID: 14390 Comm: syz.5.1969 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xba/0x230 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 xattr_find_entry+0x1a5/0x280 fs/ext4/xattr.c:334 ext4_xattr_ibody_get+0x232/0x4c0 fs/ext4/xattr.c:655 ext4_xattr_get+0x123/0x6a0 fs/ext4/xattr.c:709 ext4_get_acl+0x84/0x930 fs/ext4/acl.c:165 __get_acl+0x27e/0x410 fs/posix_acl.c:159 check_acl+0x3a/0x150 fs/namei.c:385 acl_permission_check fs/namei.c:471 [inline] generic_permission+0x497/0x690 fs/namei.c:524 do_inode_permission fs/namei.c:585 [inline] inode_permission+0x243/0x5f0 fs/namei.c:648 lookup_inode_permission_may_exec fs/namei.c:-1 [inline] may_lookup fs/namei.c:1973 [inline] link_path_walk+0x1149/0x18d0 fs/namei.c:2595 path_lookupat+0xe4/0x8c0 fs/namei.c:2803 filename_lookup+0x256/0x5d0 fs/namei.c:2833 user_path_at+0x40/0x160 fs/namei.c:3612 do_mount fs/namespace.c:4156 [inline] __do_sys_mount fs/namespace.c:4348 [inline] __se_sys_mount+0x2dc/0x420 fs/namespace.c:4325 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f621259c629 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:00007f6213442028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f6212816180 RCX: 00007f621259c629 RDX: 0000200000000080 RSI: 0000200000000040 RDI: 0000000000000000 RBP: 00007f6212632b39 R08: 0000200000000140 R09: 0000000000000000 R10: 0000000002094080 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6212816218 R14: 00007f6212816180 R15: 00007ffe00e5b068 The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x9c7 pfn:0x37dab flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000000 ffffea00028e9188 ffffea00012db308 0000000000000000 raw: 00000000000009c7 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as freed page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 14372, tgid 14365 (syz.4.1965), ts 744958078632, free_ts 745902261857 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x231/0x280 mm/page_alloc.c:1888 prep_new_page mm/page_alloc.c:1896 [inline] get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3961 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5249 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2485 folio_alloc_mpol_noprof+0x39/0x70 mm/mempolicy.c:2504 shmem_alloc_folio mm/shmem.c:1930 [inline] shmem_alloc_and_add_folio+0x445/0xf80 mm/shmem.c:1972 shmem_get_folio_gfp+0x5a9/0x1670 mm/shmem.c:2567 shmem_fault+0x179/0x390 mm/shmem.c:2768 __do_fault+0x138/0x390 mm/memory.c:5355 do_read_fault mm/memory.c:5790 [inline] do_fault mm/memory.c:5924 [inline] do_pte_missing+0x228f/0x3750 mm/memory.c:4469 handle_pte_fault mm/memory.c:6308 [inline] __handle_mm_fault mm/memory.c:6446 [inline] handle_mm_fault+0x1bec/0x3310 mm/memory.c:6615 faultin_page mm/gup.c:1126 [inline] __get_user_pages+0x165b/0x29d0 mm/gup.c:1428 populate_vma_page_range+0x2be/0x3c0 mm/gup.c:1860 __mm_populate+0x25f/0x390 mm/gup.c:1963 mm_populate include/linux/mm.h:3689 [inline] vm_mmap_pgoff+0x3aa/0x4f0 mm/util.c:586 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 page last free pid 14366 tgid 14365 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1432 [inline] free_unref_folios+0xd38/0x14c0 mm/page_alloc.c:3039 folios_put_refs+0x789/0x8d0 mm/swap.c:1002 folio_batch_release include/linux/pagevec.h:101 [inline] shmem_undo_range+0x52c/0x1660 mm/shmem.c:1149 shmem_truncate_range mm/shmem.c:1277 [inline] shmem_evict_inode+0x240/0x9e0 mm/shmem.c:1407 evict+0x61e/0xb10 fs/inode.c:846 __dentry_kill+0x1a2/0x5e0 fs/dcache.c:670 finish_dput+0xc9/0x480 fs/dcache.c:879 __fput+0x691/0xa70 fs/file_table.c:477 task_work_run+0x1d9/0x270 kernel/task_work.c:233 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x69b/0x2320 kernel/exit.c:971 do_group_exit+0x21b/0x2d0 kernel/exit.c:1112 get_signal+0x1284/0x1330 kernel/signal.c:3034 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline] exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98 __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 include/linux/entry-common.h:325 [inline] do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff888037daaf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888037daaf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888037dab000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff888037dab080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888037dab100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ==================================================================