loop0: detected capacity change from 0 to 256
exfat: Deprecated parameter 'namecase'
exFAT-fs (loop0): failed to load upcase table (idx : 0x00010000, chksum : 0x5441951d, utbl_chksum : 0xe619d30d)
==================================================================
BUG: KASAN: stack-out-of-bounds in exfat_nls_to_ucs2+0x706/0x730 fs/exfat/nls.c:619
Read of size 1 at addr ffffc90003bffcc8 by task syz.0.17/6021

CPU: 1 UID: 0 PID: 6021 Comm: syz.0.17 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 lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 exfat_nls_to_ucs2+0x706/0x730 fs/exfat/nls.c:619
 exfat_nls_to_utf16+0xa6/0xf0 fs/exfat/nls.c:647
 exfat_ioctl_set_volume_label+0x15d/0x230 fs/exfat/file.c:524
 exfat_ioctl+0x929/0x1630 fs/exfat/file.c:554
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe42fd8eec9
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:00007fffed42a368 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fe42ffe5fa0 RCX: 00007fe42fd8eec9
RDX: 00002000000001c0 RSI: 0000000041009432 RDI: 0000000000000004
RBP: 00007fe42fe11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe42ffe5fa0 R14: 00007fe42ffe5fa0 R15: 0000000000000003
 </TASK>

The buggy address belongs to stack of task syz.0.17/6021
 and is located at offset 960 in frame:
 exfat_ioctl_set_volume_label+0x0/0x230 fs/exfat/file.c:507

This frame has 3 objects:
 [32, 36) 'lossy'
 [48, 568) 'uniname'
 [704, 960) 'label'

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:0xffff888078a99fc0 pfn:0x78a99
memcg:ffff888031b53b02
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: ffff888078a99fc0 0000000000000000 00000001ffffffff ffff888031b53b02
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 12, tgid 12 (kworker/u8:0), ts 124467106609, free_ts 124465932009
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1850
 prep_new_page mm/page_alloc.c:1858 [inline]
 get_page_from_freelist+0x10a3/0x3a30 mm/page_alloc.c:3884
 __alloc_frozen_pages_noprof+0x25f/0x2470 mm/page_alloc.c:5183
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 alloc_frozen_pages_noprof mm/mempolicy.c:2487 [inline]
 alloc_pages_noprof+0x131/0x390 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+0x6f8/0x1480 mm/vmalloc.c:3897
 __vmalloc_node_noprof+0xad/0xf0 mm/vmalloc.c:3960
 alloc_thread_stack_node kernel/fork.c:311 [inline]
 dup_task_struct kernel/fork.c:881 [inline]
 copy_process+0x2c77/0x76a0 kernel/fork.c:2012
 kernel_clone+0xfc/0x930 kernel/fork.c:2609
 user_mode_thread+0xc8/0x110 kernel/fork.c:2685
 call_usermodehelper_exec_sync kernel/umh.c:132 [inline]
 call_usermodehelper_exec_work+0x6b/0x170 kernel/umh.c:163
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
 process_scheduled_works kernel/workqueue.c:3346 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page last free pid 5944 tgid 5944 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1394 [inline]
 __free_frozen_pages+0x7df/0x1160 mm/page_alloc.c:2906
 discard_slab mm/slub.c:3310 [inline]
 __put_partials+0x130/0x170 mm/slub.c:3857
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x4d/0x120 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:352
 kasan_slab_alloc include/linux/kasan.h:252 [inline]
 slab_post_alloc_hook mm/slub.c:4955 [inline]
 slab_alloc_node mm/slub.c:5265 [inline]
 kmem_cache_alloc_node_noprof+0x28a/0x770 mm/slub.c:5317
 __alloc_skb+0x2b2/0x380 net/core/skbuff.c:660
 alloc_skb include/linux/skbuff.h:1383 [inline]
 netlink_alloc_large_skb+0x69/0x140 net/netlink/af_netlink.c:1186
 netlink_sendmsg+0x698/0xdd0 net/netlink/af_netlink.c:1871
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 __sys_sendto+0x4a3/0x520 net/socket.c:2244
 __do_sys_sendto net/socket.c:2251 [inline]
 __se_sys_sendto net/socket.c:2247 [inline]
 __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2247
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffffc90003bffb80: f2 f2 f2 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00
 ffffc90003bffc00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc90003bffc80: 00 00 00 00 00 00 00 00 00 f3 f3 f3 f3 f3 f3 f3
                                              ^
 ffffc90003bffd00: f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffc90003bffd80: 00 00 00 00 f1 f1 f1 f1 f1 f1 00 00 00 f2 f2 f2
==================================================================