syz.0.282: attempt to access beyond end of device
loop0: rw=524288, sector=525144, nr_sectors = 16 limit=16
syz.0.282: attempt to access beyond end of device
loop0: rw=524288, sector=16, nr_sectors = 8 limit=16
syz.0.282: attempt to access beyond end of device
loop0: rw=524288, sector=13716630376, nr_sectors = 8 limit=16
==================================================================
BUG: KASAN: slab-use-after-free in memcpy_to_page include/linux/highmem.h:427 [inline]
BUG: KASAN: slab-use-after-free in z_erofs_transform_plain+0x38c/0x460 fs/erofs/decompressor.c:346
Read of size 4095 at addr ffff88805e610400 by task syz.0.282/6890

CPU: 0 PID: 6890 Comm: syz.0.282 Not tainted 6.6.99-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xac/0x200 mm/kasan/report.c:466
 kasan_report+0x117/0x150 mm/kasan/report.c:579
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x288/0x290 mm/kasan/generic.c:187
 __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
 memcpy_to_page include/linux/highmem.h:427 [inline]
 z_erofs_transform_plain+0x38c/0x460 fs/erofs/decompressor.c:346
 z_erofs_decompress_pcluster fs/erofs/zdata.c:1290 [inline]
 z_erofs_decompress_queue+0x16fb/0x2650 fs/erofs/zdata.c:1371
 z_erofs_runqueue+0x18a3/0x19d0 fs/erofs/zdata.c:1759
 z_erofs_readahead+0xa7c/0xd50 fs/erofs/zdata.c:1888
 read_pages+0x177/0x840 mm/readahead.c:160
 page_cache_ra_unbounded+0x692/0x770 mm/readahead.c:269
 do_page_cache_ra mm/readahead.c:299 [inline]
 force_page_cache_ra+0x2c1/0x320 mm/readahead.c:330
 force_page_cache_readahead mm/internal.h:175 [inline]
 generic_fadvise+0x44f/0x730 mm/fadvise.c:106
 vfs_fadvise mm/fadvise.c:185 [inline]
 ksys_fadvise64_64 mm/fadvise.c:199 [inline]
 __do_sys_fadvise64 mm/fadvise.c:214 [inline]
 __se_sys_fadvise64 mm/fadvise.c:212 [inline]
 __x64_sys_fadvise64+0x140/0x180 mm/fadvise.c:212
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f0dcd18e9a9
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:00007f0dcdf59038 EFLAGS: 00000246 ORIG_RAX: 00000000000000dd
RAX: ffffffffffffffda RBX: 00007f0dcd3b6080 RCX: 00007f0dcd18e9a9
RDX: 000000000000ff39 RSI: 000000000000aa17 RDI: 0000000000000005
RBP: 00007f0dcd210d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f0dcd3b6080 R15: 00007ffe939d8f38
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0001798400 refcount:2 mapcount:0 mapping:ffff888076f707c8 index:0x1 pfn:0x5e610
memcg:ffff88801c306000
aops:z_erofs_cache_aops ino:0
flags: 0xfff40000008028(uptodate|lru|private|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff40000008028 ffffea0001797fc8 ffffea000093ef08 ffff888076f707c8
raw: 0000000000000001 ffff88805e8b2000 00000002ffffffff ffff88801c306000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x192840(GFP_NOWAIT|__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 6884, tgid 6875 (syz.0.282), ts 114482277777, free_ts 76431033010
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
 prep_new_page mm/page_alloc.c:1561 [inline]
 get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
 __alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
 z_erofs_bind_cache fs/erofs/zdata.c:599 [inline]
 z_erofs_pcluster_begin fs/erofs/zdata.c:883 [inline]
 z_erofs_do_read_page+0x20c0/0x3680 fs/erofs/zdata.c:1018
 z_erofs_read_folio+0x213/0x540 fs/erofs/zdata.c:1839
 filemap_read_folio+0x167/0x760 mm/filemap.c:2420
 do_read_cache_folio+0x470/0x7e0 mm/filemap.c:3789
 erofs_bread+0x16f/0x630 fs/erofs/data.c:48
 erofs_find_target_block fs/erofs/namei.c:103 [inline]
 erofs_namei+0x28c/0xf00 fs/erofs/namei.c:177
 erofs_lookup+0x135/0x310 fs/erofs/namei.c:206
 lookup_open fs/namei.c:3466 [inline]
 open_last_lookups fs/namei.c:3556 [inline]
 path_openat+0x10b8/0x3190 fs/namei.c:3786
 do_filp_open+0x1c5/0x3d0 fs/namei.c:3816
 do_sys_openat2+0x12c/0x1c0 fs/open.c:1419
 do_sys_open fs/open.c:1434 [inline]
 __do_sys_creat fs/open.c:1512 [inline]
 __se_sys_creat fs/open.c:1506 [inline]
 __x64_sys_creat+0x90/0xb0 fs/open.c:1506
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1154 [inline]
 free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
 __slab_free+0x35e/0x410 mm/slub.c:3722
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:305
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3485 [inline]
 __kmem_cache_alloc_node+0x13e/0x260 mm/slub.c:3524
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc_node_track_caller+0xa2/0x230 mm/slab_common.c:1027
 kmemdup+0x2b/0x70 mm/util.c:131
 kmemdup include/linux/fortify-string.h:779 [inline]
 shmem_symlink+0x198/0x490 mm/shmem.c:3489
 vfs_symlink+0x138/0x2b0 fs/namei.c:4473
 do_symlinkat+0x1b2/0x3f0 fs/namei.c:4499
 __do_sys_symlink fs/namei.c:4520 [inline]
 __se_sys_symlink fs/namei.c:4518 [inline]
 __x64_sys_symlink+0x7e/0x90 fs/namei.c:4518
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff88805e610f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88805e610f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88805e611000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88805e611080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88805e611100: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================