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BUG: KASAN: stack-out-of-[  109.681891][ T6006] BUG: KASAN: stack-out-of-bounds in exfat_nls_to_ucs2 fs/exfat/nls.c:619 [inline]
BUG: KASAN: stack-out-of-[  109.681891][ T6006] BUG: KASAN: stack-out-of-bounds in exfat_nls_to_utf16+0xac8/0xc10 fs/exfat/nls.c:647
Read of size 1 at addr ffffc90003d2f710 by task syz.0.17/6006

CPU: 1 UID: 0 PID: 6006 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 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
 exfat_nls_to_ucs2 fs/exfat/nls.c:619 [inline]
 exfat_nls_to_utf16+0xac8/0xc10 fs/exfat/nls.c:647
 exfat_ioctl_set_volume_label fs/exfat/file.c:524 [inline]
 exfat_ioctl+0x818/0x1100 fs/exfat/file.c:554
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd45b22eec9
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:00007ffd11d3e078 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd45b485fa0 RCX: 00007fd45b22eec9
RDX: 00002000000007c0 RSI: 0000000041009432 RDI: 0000000000000004
RBP: 00007fd45b2b1f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd45b485fa0 R14: 00007fd45b485fa0 R15: 0000000000000003
 </TASK>

The buggy address belongs to stack of task syz.0.17/6006
 and is located at offset 304 in frame:
 exfat_ioctl+0x0/0x1100 fs/exfat/file.c:33

This frame has 7 objects:
 [32, 36) 'lossy.i'
 [48, 304) 'label.i50'
 [368, 888) 'uniname.i51'
 [1024, 1280) 'label.i'
 [1344, 1864) 'uniname.i'
 [2000, 2024) 'range.i'
 [2064, 2144) 'ia.i'

The buggy address belongs to a vmalloc virtual mapping
The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880324e1fc0 pfn:0x324e1
memcg:ffff8880305dcf02
flags: 0x80000000000000(node=0|zone=1)
raw: 0080000000000000 0000000000000000 dead000000000122 0000000000000000
raw: ffff8880324e1fc0 0000000000000000 00000001ffffffff ffff8880305dcf02
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2dc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_ZERO|__GFP_NOWARN), pid 5988, tgid 5988 (dhcpcd-run-hook), ts 108653123352, free_ts 108605315121
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1850
 prep_new_page mm/page_alloc.c:1858 [inline]
 get_page_from_freelist+0x28c0/0x2960 mm/page_alloc.c:3884
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5183
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2416
 alloc_frozen_pages_noprof mm/mempolicy.c:2487 [inline]
 alloc_pages_noprof+0xcf/0x1e0 mm/mempolicy.c:2507
 vm_area_alloc_pages mm/vmalloc.c:3647 [inline]
 __vmalloc_area_node mm/vmalloc.c:3724 [inline]
 __vmalloc_node_range_noprof+0x96c/0x12d0 mm/vmalloc.c:3897
 __vmalloc_node_noprof+0xc2/0x110 mm/vmalloc.c:3960
 alloc_thread_stack_node kernel/fork.c:311 [inline]
 dup_task_struct+0x3d4/0x830 kernel/fork.c:881
 copy_process+0x545/0x3ae0 kernel/fork.c:2012
 kernel_clone+0x224/0x7c0 kernel/fork.c:2609
 __do_sys_clone kernel/fork.c:2750 [inline]
 __se_sys_clone kernel/fork.c:2734 [inline]
 __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2734
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 28 tgid 28 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1394 [inline]
 __free_frozen_pages+0xfb6/0x1140 mm/page_alloc.c:2906
 __tlb_remove_table_free mm/mmu_gather.c:227 [inline]
 tlb_remove_table_rcu+0x85/0x100 mm/mmu_gather.c:290
 rcu_do_batch kernel/rcu/tree.c:2605 [inline]
 rcu_core kernel/rcu/tree.c:2861 [inline]
 rcu_cpu_kthread+0xbf3/0x1b50 kernel/rcu/tree.c:2949
 smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x436/0x7d0 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:
 ffffc90003d2f600: 04 f2 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90003d2f680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc90003d2f700: 00 00 f2 f2 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00
                         ^
 ffffc90003d2f780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90003d2f800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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