syz.6.4828: attempt to access beyond end of device
loop6: rw=524288, sector=525144, nr_sectors = 16 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 ffff888058846400 by task syz.6.4828/19866

CPU: 0 PID: 19866 Comm: syz.6.4828 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: 0033:0x7f1bdf18eba9
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:00007f1bdff98038 EFLAGS: 00000246 ORIG_RAX: 00000000000000dd
RAX: ffffffffffffffda RBX: 00007f1bdf3d6090 RCX: 00007f1bdf18eba9
RDX: 000000000000ff39 RSI: 0000000000000003 RDI: 0000000000000005
RBP: 00007f1bdf211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1bdf3d6128 R14: 00007f1bdf3d6090 R15: 00007ffd7f7ba318
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0001621180 refcount:2 mapcount:0 mapping:ffff88805c980d20 index:0x1 pfn:0x58846
memcg:ffff88805b866000
aops:z_erofs_cache_aops ino:0
flags: 0xfff40000008028(uptodate|lru|private|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff40000008028 ffffea0001e2a248 ffffea0001d0de88 ffff88805c980d20
raw: 0000000000000001 ffff88805caa0178 00000002ffffffff ffff88805b866000
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 19868, tgid 19862 (syz.6.4828), ts 741307152477, free_ts 741069102167
 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_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_openat fs/open.c:1450 [inline]
 __se_sys_openat fs/open.c:1445 [inline]
 __x64_sys_openat+0x139/0x160 fs/open.c:1445
 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_list+0xbe/0x860 mm/page_alloc.c:2475
 release_pages+0x1fa0/0x2220 mm/swap.c:1022
 tlb_batch_pages_flush mm/mmu_gather.c:98 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:293 [inline]
 tlb_flush_mmu+0x368/0x4f0 mm/mmu_gather.c:300
 tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:392
 exit_mmap+0x3f0/0xb50 mm/mmap.c:3315
 __mmput+0x118/0x3c0 kernel/fork.c:1355
 exit_mm+0x1da/0x2c0 kernel/exit.c:569
 do_exit+0x88e/0x23c0 kernel/exit.c:870
 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:
 ffff888058846f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888058846f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888058847000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888058847080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888058847100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================