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BUG: KASAN: stack-out-of-bounds in exfat_nls_to_ucs2 fs/exfat/nls.c:619 [inline]
BUG: KASAN: stack-out-of-bounds in exfat_nls_to_utf16+0xac8/0xc10 fs/exfat/nls.c:647
Read of size 1 at addr ffffc9000a55f6f0 by task syz.0.118/6656

CPU: 0 UID: 0 PID: 6656 Comm: syz.0.118 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/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb53397eec9
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:00007fb531be6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fb533bd5fa0 RCX: 00007fb53397eec9
RDX: 00002000000001c0 RSI: 0000000041009432 RDI: 0000000000000006
RBP: 00007fb533a01f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb533bd6038 R14: 00007fb533bd5fa0 R15: 00007fff0bea3438
 </TASK>

The buggy address belongs to stack of task syz.0.118/6656
 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:0x0 pfn:0x230b9
memcg:ffff88803c77d902
flags: 0x80000000000000(node=0|zone=1)
raw: 0080000000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff ffff88803c77d902
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 6638, tgid 6638 (syz.3.116), ts 137259846325, free_ts 117136446647
 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_clone3 kernel/fork.c:2911 [inline]
 __se_sys_clone3+0x256/0x2d0 kernel/fork.c:2890
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5849 tgid 5849 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
 discard_slab mm/slub.c:3301 [inline]
 __put_partials+0x149/0x170 mm/slub.c:3848
 __slab_free+0x29e/0x370 mm/slub.c:5882
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:352
 kasan_slab_alloc include/linux/kasan.h:252 [inline]
 slab_post_alloc_hook mm/slub.c:4946 [inline]
 slab_alloc_node mm/slub.c:5245 [inline]
 kmem_cache_alloc_noprof+0x181/0x6b0 mm/slub.c:5252
 getname_flags+0xb8/0x540 fs/namei.c:146
 getname include/linux/fs.h:2922 [inline]
 getname_maybe_null include/linux/fs.h:2929 [inline]
 vfs_fstatat+0x43/0x170 fs/stat.c:370
 __do_sys_newfstatat fs/stat.c:542 [inline]
 __se_sys_newfstatat fs/stat.c:536 [inline]
 __x64_sys_newfstatat+0x116/0x190 fs/stat.c:536
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffffc9000a55f580: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 04 f2 00 00
 ffffc9000a55f600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc9000a55f680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f2 f2
                                                             ^
 ffffc9000a55f700: f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00 00 00 00
 ffffc9000a55f780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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