Linux kernel crash report:
loop0: detected capacity change from 0 to 64
==================================================================
BUG: KASAN: slab-out-of-bounds in hfs_asc2mac+0x467/0x9a0 fs/hfs/trans.c:133
Write of size 1 at addr ffff88801848314e by task syz-executor391/3632

CPU: 0 PID: 3632 Comm: syz-executor391 Not tainted 6.1.0-rc6-syzkaller-00012-g4312098baf37 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106
 print_address_description+0x74/0x340 mm/kasan/report.c:284
 print_report+0x107/0x1f0 mm/kasan/report.c:395
 kasan_report+0xcd/0x100 mm/kasan/report.c:495
 hfs_asc2mac+0x467/0x9a0 fs/hfs/trans.c:133
 hfs_cat_build_key+0x92/0x170 fs/hfs/catalog.c:28
 hfs_lookup+0x1ab/0x2c0 fs/hfs/dir.c:31
 lookup_open fs/namei.c:3391 [inline]
 open_last_lookups fs/namei.c:3481 [inline]
 path_openat+0x10e6/0x2df0 fs/namei.c:3710
 do_filp_open+0x264/0x4f0 fs/namei.c:3740
 do_sys_openat2+0x124/0x4e0 fs/open.c:1310
 do_sys_open fs/open.c:1326 [inline]
 __do_sys_open fs/open.c:1334 [inline]
 __se_sys_open fs/open.c:1330 [inline]
 __x64_sys_open+0x221/0x270 fs/open.c:1330
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fdc79c9d839
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 14 00 00 90 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd57f47648 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdc79c9d839
RDX: 0000000000000100 RSI: 0000000000002000 RDI: 0000000020000800
RBP: 00007fdc79c5d0d0 R08: 0000000000000245 R09: 0000000000000000
R10: 00007ffd57f47510 R11: 0000000000000246 R12: 00007fdc79c5d160
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Allocated by task 3632:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x3d/0x60 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:371 [inline]
 __kasan_kmalloc+0x97/0xb0 mm/kasan/common.c:380
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __do_kmalloc_node mm/slab_common.c:955 [inline]
 __kmalloc+0xaf/0x1a0 mm/slab_common.c:968
 kmalloc include/linux/slab.h:558 [inline]
 hfs_find_init+0x8b/0x1e0 fs/hfs/bfind.c:21
 hfs_lookup+0x105/0x2c0 fs/hfs/dir.c:28
 lookup_open fs/namei.c:3391 [inline]
 open_last_lookups fs/namei.c:3481 [inline]
 path_openat+0x10e6/0x2df0 fs/namei.c:3710
 do_filp_open+0x264/0x4f0 fs/namei.c:3740
 do_sys_openat2+0x124/0x4e0 fs/open.c:1310
 do_sys_open fs/open.c:1326 [inline]
 __do_sys_open fs/open.c:1334 [inline]
 __se_sys_open fs/open.c:1330 [inline]
 __x64_sys_open+0x221/0x270 fs/open.c:1330
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff888018483100
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 78 bytes inside of
 96-byte region [ffff888018483100, ffff888018483160)

The buggy address belongs to the physical page:
page:ffffea00006120c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x18483
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 dead000000000100 dead000000000122 ffff888012841780
raw: 0000000000000000 0000000080200020 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 1, tgid 1 (swapper/0), ts 2311131230, free_ts 0
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x742/0x7c0 mm/page_alloc.c:4288
 __alloc_pages+0x259/0x560 mm/page_alloc.c:5555
 alloc_page_interleave+0x22/0x1c0 mm/mempolicy.c:2118
 alloc_slab_page+0x70/0xf0 mm/slub.c:1794
 allocate_slab+0x5e/0x4b0 mm/slub.c:1939
 new_slab mm/slub.c:1992 [inline]
 ___slab_alloc+0x782/0xe20 mm/slub.c:3180
 __slab_alloc mm/slub.c:3279 [inline]
 slab_alloc_node mm/slub.c:3364 [inline]
 __kmem_cache_alloc_node+0x252/0x310 mm/slub.c:3437
 __do_kmalloc_node mm/slab_common.c:954 [inline]
 __kmalloc_node_track_caller+0x9c/0x190 mm/slab_common.c:975
 __do_krealloc mm/slab_common.c:1348 [inline]
 krealloc+0x61/0xf0 mm/slab_common.c:1381
 add_sysfs_param+0x134/0x800 kernel/params.c:660
 kernel_add_sysfs_param+0xb0/0x126 kernel/params.c:812
 param_sysfs_builtin+0x1fb/0x2a5 kernel/params.c:851
 param_sysfs_init+0x68/0x6c kernel/params.c:970
 do_one_initcall+0x1c9/0x400 init/main.c:1303
 do_initcall_level+0x168/0x218 init/main.c:1376
 do_initcalls+0x4b/0x8c init/main.c:1392
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888018483000: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff888018483080: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
>ffff888018483100: 00 00 00 00 00 00 00 00 00 06 fc fc fc fc fc fc
                                              ^
 ffff888018483180: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
 ffff888018483200: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
==================================================================


Fix patch:
diff --git a/fs/hfs/trans.c b/fs/hfs/trans.c
index 39f5e343bf4d..fdb0edb8a607 100644
--- a/fs/hfs/trans.c
+++ b/fs/hfs/trans.c
@@ -109,7 +109,7 @@ void hfs_asc2mac(struct super_block *sb, struct hfs_name *out, const struct qstr
 	if (nls_io) {
 		wchar_t ch;
 
-		while (srclen > 0) {
+		while (srclen > 0 && dstlen > 0) {
 			size = nls_io->char2uni(src, srclen, &ch);
 			if (size < 0) {
 				ch = '?';