loop4: detected capacity change from 0 to 256
exfat: Deprecated parameter 'namecase'
exFAT-fs (loop4): failed to load upcase table (idx : 0x00010000, chksum : 0x5441951d, utbl_chksum : 0xe619d30d)
==================================================================
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 ffffc9000bc1f6f0 by task syz.4.2391/18451

CPU: 1 UID: 0 PID: 18451 Comm: syz.4.2391 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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+0x815/0x1100 fs/exfat/file.c:554
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/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: 0033:0x7fdb6858eec9
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:00007fdb69458038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fdb687e5fa0 RCX: 00007fdb6858eec9
RDX: 00002000000001c0 RSI: 0000000041009432 RDI: 0000000000000004
RBP: 00007fdb68611f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdb687e6038 R14: 00007fdb687e5fa0 R15: 00007ffd35944068
 </TASK>

The buggy address belongs to stack of task syz.4.2391/18451
 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:0xffff888051647c80 pfn:0x51647
memcg:ffff8880321cfe82
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: ffff888051647c80 0000000000000000 00000001ffffffff ffff8880321cfe82
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 18313, tgid 18313 (syz.6.2341), ts 1010050534141, free_ts 1009854116532
 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+0x2365/0x2440 mm/page_alloc.c:3884
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5183
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 alloc_frozen_pages_noprof mm/mempolicy.c:2487 [inline]
 alloc_pages_noprof+0xa9/0x190 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+0x54b/0x3c00 kernel/fork.c:2012
 kernel_clone+0x21e/0x840 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 18301 tgid 18299 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1394 [inline]
 __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2906
 discard_slab mm/slub.c:3302 [inline]
 __put_partials+0x146/0x170 mm/slub.c:3849
 put_cpu_partial+0x1f2/0x2e0 mm/slub.c:3924
 __slab_free+0x2b9/0x390 mm/slub.c:5883
 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:4947 [inline]
 slab_alloc_node mm/slub.c:5246 [inline]
 kmem_cache_alloc_node_noprof+0x433/0x710 mm/slub.c:5298
 __alloc_skb+0x112/0x2d0 net/core/skbuff.c:660
 alloc_skb include/linux/skbuff.h:1383 [inline]
 nlmsg_new include/net/netlink.h:1055 [inline]
 inet_ifmcaddr_notify+0x7e/0x150 net/ipv4/igmp.c:1481
 __ip_mc_dec_group+0x40b/0x690 net/ipv4/igmp.c:1778
 inetdev_event+0x2a7/0x15b0 net/ipv4/devinet.c:1641
 notifier_call_chain+0x1b6/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
 call_netdevice_notifiers net/core/dev.c:2281 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9705
 do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3151

Memory state around the buggy address:
 ffffc9000bc1f580: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 04 f2 00 00
 ffffc9000bc1f600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc9000bc1f680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f2 f2
                                                             ^
 ffffc9000bc1f700: f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00 00 00 00
 ffffc9000bc1f780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================