loop4: rw=524288, sector=67108872, nr_sectors = 16 limit=16
syz.4.238: attempt to access beyond end of device
loop4: rw=524288, sector=720, nr_sectors = 8 limit=16
==================================================================
BUG: KASAN: use-after-free in z_erofs_transform_plain+0x3a4/0x4ac fs/erofs/decompressor.c:350
Read of size 4095 at addr ffff0000f372b400 by task syz.4.238/5161

CPU: 0 PID: 5161 Comm: syz.4.238 Not tainted 6.1.130-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call trace:
 dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0x174/0x4c0 mm/kasan/report.c:427
 kasan_report+0xd4/0x130 mm/kasan/report.c:531
 kasan_check_range+0x264/0x2a4 mm/kasan/generic.c:189
 memcpy+0x48/0x90 mm/kasan/shadow.c:65
 z_erofs_transform_plain+0x3a4/0x4ac fs/erofs/decompressor.c:350
 z_erofs_decompress+0x9c/0xd4 fs/erofs/decompressor.c:439
 z_erofs_decompress_pcluster fs/erofs/zdata.c:1175 [inline]
 z_erofs_decompress_queue+0x13b0/0x2388 fs/erofs/zdata.c:1258
 z_erofs_runqueue+0x166c/0x18b4 fs/erofs/zdata.c:1616
 z_erofs_readahead+0x988/0xe04 fs/erofs/zdata.c:1760
 read_pages+0x168/0x6a0 mm/readahead.c:161
 page_cache_ra_unbounded+0x46c/0x58c mm/readahead.c:270
 do_page_cache_ra mm/readahead.c:300 [inline]
 force_page_cache_ra+0x248/0x2b0 mm/readahead.c:331
 force_page_cache_readahead mm/internal.h:125 [inline]
 generic_fadvise+0x3f8/0x648 mm/fadvise.c:107
 vfs_fadvise mm/fadvise.c:185 [inline]
 ksys_fadvise64_64 mm/fadvise.c:199 [inline]
 __do_sys_fadvise64_64 mm/fadvise.c:207 [inline]
 __se_sys_fadvise64_64 mm/fadvise.c:205 [inline]
 __arm64_sys_fadvise64_64+0x12c/0x174 mm/fadvise.c:205
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

The buggy address belongs to the physical page:
page:000000000c2f10dc refcount:3 mapcount:0 mapping:00000000a0803a33 index:0x1 pfn:0x13372b
memcg:ffff0000d3f82000
aops:managed_cache_aops ino:0
flags: 0x5ffc00000002004(uptodate|private|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000002004 0000000000000000 dead000000000122 ffff0000e32d97d0
raw: 0000000000000001 ffff0000e3197000 00000003ffffffff ffff0000d3f82000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000f372bf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff0000f372bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff0000f372c000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff0000f372c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
 ffff0000f372c100: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
==================================================================