==================================================================
BUG: KASAN: use-after-free in copy_page_from_iter_atomic+0x978/0x1214 lib/iov_iter.c:978
Read of size 4096 at addr ffff0000c7fd6000 by task kworker/u4:5/598

CPU: 1 PID: 598 Comm: kworker/u4:5 Not tainted 5.15.180-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: loop3 loop_workfn
Call trace:
 dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106
 print_address_description+0x78/0x30c mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xec/0x15c mm/kasan/report.c:451
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x270/0x2b0 mm/kasan/generic.c:189
 memcpy+0x90/0xe8 mm/kasan/shadow.c:65
 copy_page_from_iter_atomic+0x978/0x1214 lib/iov_iter.c:978
 generic_perform_write+0x284/0x480 mm/filemap.c:3793
 __generic_file_write_iter+0x23c/0x454 mm/filemap.c:3912
 generic_file_write_iter+0xb0/0x1b4 mm/filemap.c:3944
 do_iter_readv_writev+0x3a0/0x4f8 fs/read_write.c:-1
 do_iter_write+0x1c4/0x670 fs/read_write.c:855
 vfs_iter_write+0x88/0xac fs/read_write.c:896
 lo_write_bvec+0x364/0xa24 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+0x1a18/0x20d0 drivers/block/loop.c:2274
 loop_workfn+0x50/0x64 drivers/block/loop.c:2298
 process_one_work+0x79c/0x1140 kernel/workqueue.c:2310
 worker_thread+0x8f4/0x101c kernel/workqueue.c:2457
 kthread+0x374/0x454 kernel/kthread.c:334
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870

The buggy address belongs to the page:
page:0000000039bfacc7 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x107fd6
flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000000 fffffc000393e848 fffffc0003a27388 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000c7fd5f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff0000c7fd5f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff0000c7fd6000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff0000c7fd6080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000c7fd6100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================