KCSAN: data-race in file_update_time / inode_set_ctime

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in file_update_time / inode_set_ctime_current (2) fs	6				1	247d	247d	0/29	auto-obsoleted due to no activity on 2025/01/15 18:17
upstream	KCSAN: data-race in file_update_time / inode_set_ctime_current ext4	6				1	448d	448d	0/29	auto-obsoleted due to no activity on 2024/06/07 07:08

==================================================================
BUG: KCSAN: data-race in file_update_time / inode_set_ctime_current

write to 0xffff888106eef140 of 8 bytes by task 11549 on cpu 0:
 inode_set_ctime_current+0x533/0x770 fs/inode.c:2763
 inode_update_timestamps+0x84/0x270 fs/inode.c:2018
 generic_update_time fs/inode.c:2057 [inline]
 inode_update_time fs/inode.c:2077 [inline]
 __file_update_time fs/inode.c:2305 [inline]
 file_update_time+0x20e/0x2b0 fs/inode.c:2335
 ext4_page_mkwrite+0x18b/0xba0 fs/ext4/inode.c:6577
 do_page_mkwrite mm/memory.c:3378 [inline]
 wp_page_shared mm/memory.c:3779 [inline]
 do_wp_page+0xe5a/0x2400 mm/memory.c:3998
 handle_pte_fault mm/memory.c:6085 [inline]
 __handle_mm_fault mm/memory.c:6212 [inline]
 handle_mm_fault+0x77d/0x2be0 mm/memory.c:6381
 do_user_addr_fault+0x636/0x1090 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

read to 0xffff888106eef140 of 8 bytes by task 11556 on cpu 1:
 inode_get_ctime_sec include/linux/fs.h:1743 [inline]
 inode_get_ctime include/linux/fs.h:1753 [inline]
 inode_needs_update_time fs/inode.c:2288 [inline]
 file_update_time+0xca/0x2b0 fs/inode.c:2331
 ext4_page_mkwrite+0x18b/0xba0 fs/ext4/inode.c:6577
 do_page_mkwrite mm/memory.c:3378 [inline]
 do_shared_fault mm/memory.c:5666 [inline]
 do_fault mm/memory.c:5728 [inline]
 do_pte_missing mm/memory.c:4251 [inline]
 handle_pte_fault mm/memory.c:6069 [inline]
 __handle_mm_fault mm/memory.c:6212 [inline]
 handle_mm_fault+0x15cb/0x2be0 mm/memory.c:6381
 do_user_addr_fault+0x793/0x1090 arch/x86/mm/fault.c:1387
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
 rep_movs_alternative+0x4a/0x90 arch/x86/lib/copy_user_64.S:68
 copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline]
 raw_copy_to_user arch/x86/include/asm/uaccess_64.h:147 [inline]
 _inline_copy_to_user include/linux/uaccess.h:197 [inline]
 _copy_to_user+0x7c/0xa0 lib/usercopy.c:26
 copy_to_user include/linux/uaccess.h:225 [inline]
 rng_dev_read+0x3ef/0x740 drivers/char/hw_random/core.c:258
 do_loop_readv_writev fs/read_write.c:847 [inline]
 vfs_readv+0x3f8/0x690 fs/read_write.c:1020
 do_preadv fs/read_write.c:1132 [inline]
 __do_sys_preadv fs/read_write.c:1179 [inline]
 __se_sys_preadv fs/read_write.c:1174 [inline]
 __x64_sys_preadv+0xfd/0x1c0 fs/read_write.c:1174
 x64_sys_call+0x1503/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:296
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000000000b9 -> 0x00000000000000ba

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 11556 Comm: syz.5.2620 Not tainted 6.16.0-rc6-syzkaller-00279-gbf61759db409 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================
EXT4-fs error (device loop5): ext4_mb_mark_diskspace_used:4113: comm syz.5.2620: Allocating blocks 497-513 which overlap fs metadata