loop3: rw=524288, sector=13716630376, nr_sectors = 8 limit=16
==================================================================
BUG: KASAN: slab-out-of-bounds in z_erofs_transform_plain+0x37a/0x490 fs/erofs/decompressor.c:350
Read of size 4095 at addr ffff888031356400 by task syz.3.617/6854

CPU: 0 PID: 6854 Comm: syz.3.617 Not tainted 6.1.141-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x220 mm/kasan/report.c:427
 kasan_report+0x10b/0x140 mm/kasan/report.c:531
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x27b/0x290 mm/kasan/generic.c:189
 memcpy+0x25/0x60 mm/kasan/shadow.c:65
 z_erofs_transform_plain+0x37a/0x490 fs/erofs/decompressor.c:350
 z_erofs_decompress_pcluster fs/erofs/zdata.c:1175 [inline]
 z_erofs_decompress_queue+0x1577/0x2370 fs/erofs/zdata.c:1258
 z_erofs_runqueue+0x1a83/0x1bc0 fs/erofs/zdata.c:1616
 z_erofs_readahead+0xa36/0xdc0 fs/erofs/zdata.c:1760
 read_pages+0x173/0x840 mm/readahead.c:161
 page_cache_ra_unbounded+0x690/0x770 mm/readahead.c:270
 do_page_cache_ra mm/readahead.c:300 [inline]
 force_page_cache_ra+0x2bd/0x320 mm/readahead.c:331
 force_page_cache_readahead mm/internal.h:125 [inline]
 generic_fadvise+0x44e/0x6c0 mm/fadvise.c:107
 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+0x139/0x180 mm/fadvise.c:212
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff693f8e929
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:00007ff694dff038 EFLAGS: 00000246 ORIG_RAX: 00000000000000dd
RAX: ffffffffffffffda RBX: 00007ff6941b5fa0 RCX: 00007ff693f8e929
RDX: 000000000000ff39 RSI: 000000000000aa1f RDI: 0000000000000005
RBP: 00007ff694010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007ff6941b5fa0 R15: 00007ffed4169c38
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0000c4d580 refcount:2 mapcount:0 mapping:ffff888071b75298 index:0x1 pfn:0x31356
memcg:ffff888055014000
aops:managed_cache_aops ino:0
flags: 0xfff40000002014(uptodate|lru|private|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff40000002014 ffffea0001ebff08 ffffea0001417c08 ffff888071b75298
raw: 0000000000000001 ffff88807188c9c0 00000002ffffffff ffff888055014000
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 6854, tgid 6851 (syz.3.617), ts 362118042176, free_ts 362098279853
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2532
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x1a26/0x1ac0 mm/page_alloc.c:4328
 __alloc_pages+0x1df/0x4e0 mm/page_alloc.c:5614
 z_erofs_bind_cache fs/erofs/zdata.c:482 [inline]
 z_erofs_do_read_page+0x19be/0x39e0 fs/erofs/zdata.c:860
 z_erofs_read_folio+0x256/0x5c0 fs/erofs/zdata.c:1705
 filemap_read_folio+0x160/0x760 mm/filemap.c:2490
 do_read_cache_folio+0x2a0/0x760 mm/filemap.c:3627
 erofs_bread+0x18e/0x670 fs/erofs/data.c:50
 erofs_find_target_block fs/erofs/namei.c:102 [inline]
 erofs_namei+0x28f/0xf00 fs/erofs/namei.c:175
 erofs_lookup+0x14b/0x390 fs/erofs/namei.c:204
 __lookup_slow+0x27d/0x3a0 fs/namei.c:1690
 lookup_slow+0x53/0x70 fs/namei.c:1707
 walk_component fs/namei.c:1998 [inline]
 link_path_walk+0x928/0xe50 fs/namei.c:2325
 path_openat+0x276/0x2e70 fs/namei.c:3779
 do_filp_open+0x1c1/0x3c0 fs/namei.c:3810
 do_sys_openat2+0x142/0x490 fs/open.c:1318
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1459 [inline]
 free_pcp_prepare mm/page_alloc.c:1509 [inline]
 free_unref_page_prepare+0x8b4/0x9a0 mm/page_alloc.c:3384
 free_unref_page_list+0xbb/0x8e0 mm/page_alloc.c:3525
 release_pages+0x1f92/0x2200 mm/swap.c:1035
 tlb_batch_pages_flush mm/mmu_gather.c:59 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:254 [inline]
 tlb_flush_mmu+0xff/0x210 mm/mmu_gather.c:261
 tlb_finish_mmu+0xbd/0x1c0 mm/mmu_gather.c:361
 exit_mmap+0x343/0x8e0 mm/mmap.c:3250
 __mmput+0x118/0x3c0 kernel/fork.c:1200
 exit_mm+0x1e6/0x2c0 kernel/exit.c:565
 do_exit+0x8b9/0x2400 kernel/exit.c:858
 do_group_exit+0x217/0x2d0 kernel/exit.c:1021
 __do_sys_exit_group kernel/exit.c:1032 [inline]
 __se_sys_exit_group kernel/exit.c:1030 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1030
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff888031356f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888031357000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888031357080: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
                                                 ^
 ffff888031357100: fc fc 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888031357180: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
==================================================================