loop3: detected capacity change from 0 to 4096
EXT4-fs (loop3): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
==================================================================
BUG: KCSAN: data-race in _copy_to_iter / memcpy_and_pad

read to 0xffff88812b4b9400 of 512 bytes by task 8826 on cpu 1:
 instrument_copy_to_user include/linux/instrumented.h:130 [inline]
 copy_to_user_iter lib/iov_iter.c:24 [inline]
 iterate_ubuf include/linux/iov_iter.h:30 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:302 [inline]
 iterate_and_advance include/linux/iov_iter.h:330 [inline]
 _copy_to_iter+0x130/0xea0 lib/iov_iter.c:197
 copy_page_to_iter+0x174/0x210 lib/iov_iter.c:374
 copy_folio_to_iter include/linux/uio.h:204 [inline]
 filemap_read+0x3ed/0xa20 mm/filemap.c:2875
 blkdev_read_iter+0x21e/0x2d0 block/fops.c:832
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x699/0x7c0 fs/read_write.c:574
 ksys_read+0xdc/0x1a0 fs/read_write.c:716
 __do_sys_read fs/read_write.c:725 [inline]
 __se_sys_read fs/read_write.c:723 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:723
 x64_sys_call+0x2135/0x2550 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff88812b4b9492 of 54 bytes by task 12661 on cpu 0:
 memcpy_and_pad+0x5a/0x80 lib/string_helpers.c:1009
 ext4_sample_last_mounted fs/ext4/file.c:951 [inline]
 ext4_file_open+0x529/0x5f0 fs/ext4/file.c:973
 do_dentry_open+0x49f/0xa60 fs/open.c:996
 vfs_open+0x37/0x1e0 fs/open.c:1101
 do_open fs/namei.c:4837 [inline]
 path_openat+0xc01/0x10d0 fs/namei.c:5000
 do_file_open+0x16c/0x290 fs/namei.c:5029
 do_sys_openat2+0xa0/0x130 fs/open.c:1417
 do_sys_open fs/open.c:1423 [inline]
 __do_sys_creat fs/open.c:1501 [inline]
 __se_sys_creat fs/open.c:1495 [inline]
 __x64_sys_creat+0x65/0x90 fs/open.c:1495
 x64_sys_call+0xea6/0x2550 arch/x86/include/generated/asm/syscalls_64.h:86
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 12661 Comm: syz.3.2688 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================
EXT4-fs error (device loop3): ext4_do_update_inode:5801: inode #15: comm syz.3.2688: corrupted inode contents
EXT4-fs error (device loop3): ext4_dirty_inode:6731: inode #15: comm syz.3.2688: mark_inode_dirty error
EXT4-fs error (device loop3): ext4_do_update_inode:5801: inode #15: comm syz.3.2688: corrupted inode contents
EXT4-fs error (device loop3): __ext4_ext_dirty:207: inode #15: comm syz.3.2688: mark_inode_dirty error
EXT4-fs error (device loop3): ext4_do_update_inode:5801: inode #15: comm syz.3.2688: corrupted inode contents
EXT4-fs error (device loop3): __ext4_ext_dirty:207: inode #15: comm syz.3.2688: mark_inode_dirty error
EXT4-fs error (device loop3): ext4_do_update_inode:5801: inode #15: comm syz.3.2688: corrupted inode contents
EXT4-fs error (device loop3): ext4_truncate:4721: inode #15: comm syz.3.2688: mark_inode_dirty error
EXT4-fs error (device loop3) in ext4_setattr:6247: Corrupt filesystem
EXT4-fs error (device loop3): ext4_do_update_inode:5801: inode #15: comm syz.3.2688: corrupted inode contents