==================================================================
BUG: KASAN: use-after-free in copy_page_from_iter_atomic+0x8e3/0x1230 lib/iov_iter.c:978
Read of size 4096 at addr ffff88806324f000 by task kworker/u4:1/144

CPU: 0 PID: 144 Comm: kworker/u4:1 Not tainted 5.15.178-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: loop5 loop_workfn
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 print_address_description+0x63/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0x16b/0x1c0 mm/kasan/report.c:451
 kasan_check_range+0x27e/0x290 mm/kasan/generic.c:189
 memcpy+0x25/0x60 mm/kasan/shadow.c:65
 copy_page_from_iter_atomic+0x8e3/0x1230 lib/iov_iter.c:978
 generic_perform_write+0x33a/0x5b0 mm/filemap.c:3793
 __generic_file_write_iter+0x243/0x4f0 mm/filemap.c:3912
 generic_file_write_iter+0xa7/0x1b0 mm/filemap.c:3944
 do_iter_readv_writev+0x594/0x7a0
 do_iter_write+0x1e6/0x760 fs/read_write.c:855
 lo_write_bvec+0x297/0x740 drivers/block/loop.c:316
 lo_write_simple drivers/block/loop.c:338 [inline]
 do_req_filebacked drivers/block/loop.c:656 [inline]
 loop_handle_cmd drivers/block/loop.c:2234 [inline]
 loop_process_work+0x2309/0x2af0 drivers/block/loop.c:2274
 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

The buggy address belongs to the page:
page:ffffea00018c93c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x6324f
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea00008df508 ffffea0001e49f88 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x100dc0(GFP_USER|__GFP_ZERO), pid 6009, ts 274234837345, free_ts 274506730461
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x3b78/0x3d40 mm/page_alloc.c:4192
 __alloc_pages+0x272/0x700 mm/page_alloc.c:5465
 lbmLogInit fs/jfs/jfs_logmgr.c:1824 [inline]
 lmLogInit+0x376/0x1c90 fs/jfs/jfs_logmgr.c:1278
 open_inline_log fs/jfs/jfs_logmgr.c:1183 [inline]
 lmLogOpen+0x552/0x1030 fs/jfs/jfs_logmgr.c:1077
 jfs_mount_rw+0xe3/0x640 fs/jfs/jfs_mount.c:253
 jfs_fill_super+0x69f/0xc70 fs/jfs/super.c:570
 mount_bdev+0x2c9/0x3f0 fs/super.c:1400
 legacy_get_tree+0xeb/0x180 fs/fs_context.c:611
 vfs_get_tree+0x88/0x270 fs/super.c:1530
 do_new_mount+0x2ba/0xb40 fs/namespace.c:3012
 do_mount fs/namespace.c:3355 [inline]
 __do_sys_mount fs/namespace.c:3563 [inline]
 __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3540
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0xc34/0xcf0 mm/page_alloc.c:3317
 free_unref_page+0x95/0x2d0 mm/page_alloc.c:3396
 lbmLogShutdown fs/jfs/jfs_logmgr.c:1872 [inline]
 lmLogShutdown+0x4f8/0x960 fs/jfs/jfs_logmgr.c:1692
 lmLogClose+0x293/0x530 fs/jfs/jfs_logmgr.c:1468
 jfs_remount+0x431/0x6a0 fs/jfs/super.c:471
 reconfigure_super+0x43a/0x870 fs/super.c:938
 do_remount fs/namespace.c:2668 [inline]
 path_mount+0xceb/0x10a0 fs/namespace.c:3334
 do_mount fs/namespace.c:3355 [inline]
 __do_sys_mount fs/namespace.c:3563 [inline]
 __se_sys_mount+0x2d5/0x3c0 fs/namespace.c:3540
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Memory state around the buggy address:
 ffff88806324ef00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806324ef80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88806324f000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88806324f080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806324f100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================