syz.1.297: attempt to access beyond end of device
loop1: rw=524288, sector=720, nr_sectors = 16 limit=16
syz.1.297: attempt to access beyond end of device
loop1: rw=524288, sector=525144, nr_sectors = 16 limit=16
syz.1.297: attempt to access beyond end of device
loop1: rw=524288, sector=16, nr_sectors = 8 limit=16
syz.1.297: attempt to access beyond end of device
loop1: rw=524288, sector=13716630376, nr_sectors = 8 limit=16
==================================================================
BUG: KASAN: use-after-free in memcpy_to_page include/linux/highmem.h:427 [inline]
BUG: KASAN: use-after-free in z_erofs_transform_plain+0x38c/0x460 fs/erofs/decompressor.c:346
Read of size 4095 at addr ffff888065263400 by task syz.1.297/7214

CPU: 1 PID: 7214 Comm: syz.1.297 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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/0x220 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 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:1296 [inline]
 z_erofs_decompress_queue+0x16fb/0x2660 fs/erofs/zdata.c:1377
 z_erofs_runqueue+0x18a3/0x19d0 fs/erofs/zdata.c:1774
 z_erofs_readahead+0xa7c/0xd50 fs/erofs/zdata.c:1903
 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: 0033:0x7f985ab8eba9
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:00007f985ba52038 EFLAGS: 00000246 ORIG_RAX: 00000000000000dd
RAX: ffffffffffffffda RBX: 00007f985add5fa0 RCX: 00007f985ab8eba9
RDX: 000000000000ff39 RSI: 000000000000aa17 RDI: 0000000000000004
RBP: 00007f985ac11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f985add6038 R14: 00007f985add5fa0 R15: 00007ffd2ba10908
 </TASK>

The buggy address belongs to the physical page:
page:ffffea00019498c0 refcount:2 mapcount:0 mapping:ffff888060519278 index:0x1 pfn:0x65263
memcg:ffff8880248a6000
aops:z_erofs_cache_aops ino:0
flags: 0xfff40000008028(uptodate|lru|private|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff40000008028 ffffea0001949888 ffffea00015fe748 ffff888060519278
raw: 0000000000000001 ffff88807757e000 00000002ffffffff ffff8880248a6000
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 7214, tgid 7212 (syz.1.297), ts 197467300376, free_ts 195994746876
 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:605 [inline]
 z_erofs_pcluster_begin fs/erofs/zdata.c:889 [inline]
 z_erofs_do_read_page+0x20c0/0x3680 fs/erofs/zdata.c:1024
 z_erofs_read_folio+0x213/0x540 fs/erofs/zdata.c:1854
 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_slow+0x281/0x3b0 fs/namei.c:1694
 lookup_slow+0x53/0x70 fs/namei.c:1711
 walk_component fs/namei.c:2002 [inline]
 link_path_walk+0x970/0xe00 fs/namei.c:2329
 path_lookupat+0x9d/0x440 fs/namei.c:2482
 filename_lookup+0x1f4/0x510 fs/namei.c:2512
 user_path_at_empty+0x42/0x60 fs/namei.c:2909
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
 vfree+0x1a6/0x320 mm/vmalloc.c:2868
 kcov_put kernel/kcov.c:438 [inline]
 kcov_close+0x2b/0x50 kernel/kcov.c:534
 __fput+0x234/0x970 fs/file_table.c:384
 task_work_run+0x1ce/0x250 kernel/task_work.c:239
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0x90b/0x23c0 kernel/exit.c:883
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
 __do_sys_exit_group kernel/exit.c:1035 [inline]
 __se_sys_exit_group kernel/exit.c:1033 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1033
 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:
 ffff888065263f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888065263f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888065264000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888065264080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888065264100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================