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BUG: KASAN: use-after-free in copy_page_from_iter_atomic+0x974/0x123c lib/iov_iter.c:978
Read of size 4096 at addr ffff0000cb700000 by task kworker/u4:2/148

CPU: 1 PID: 148 Comm: kworker/u4:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: loop0 loop_workfn
Call trace:
 dump_backtrace+0x0/0x458 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+0xf4/0x15c 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/0x158 mm/kasan/report.c:451
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x268/0x2a0 mm/kasan/generic.c:189
 memcpy+0x90/0xe8 mm/kasan/shadow.c:65
 copy_page_from_iter_atomic+0x974/0x123c lib/iov_iter.c:978
 generic_perform_write+0x284/0x488 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+0x3a8/0x50c 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+0x364/0xa30 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:2235 [inline]
 loop_process_work+0x1b98/0x22a0 drivers/block/loop.c:2275
 loop_workfn+0x50/0x64 drivers/block/loop.c:2299
 process_one_work+0x79c/0x1138 kernel/workqueue.c:2310
 worker_thread+0x8f4/0x1034 kernel/workqueue.c:2457
 kthread+0x374/0x454 kernel/kthread.c:334
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:856

The buggy address belongs to the page:
page:00000000521e089d refcount:1 mapcount:-512 mapping:0000000000000000 index:0x0 pfn:0x10b700
memcg:ffff0000c924eb02
flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000000 0000000000000000 0000000000000000 0000000000000000
raw: 0000000000000000 ffff0000d144c4e0 00000001fffffdff ffff0000c924eb02
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000cb6fff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff0000cb6fff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff0000cb700000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                   ^
 ffff0000cb700080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff0000cb700100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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