random: fix data races at timer_rand_state
Fields in "struct timer_rand_state" could be accessed concurrently.
Lockless plain reads and writes result in data races. Fix them by adding
pairs of READ|WRITE_ONCE(). The data races were reported by KCSAN,
BUG: KCSAN: data-race in add_timer_randomness / add_timer_randomness
write to 0xffff9f320a0a01d0 of 8 bytes by interrupt on cpu 22:
add_timer_randomness+0x100/0x190
add_timer_randomness at drivers/char/random.c:1152
add_disk_randomness+0x85/0x280
scsi_end_request+0x43a/0x4a0
scsi_io_completion+0xb7/0x7e0
scsi_finish_command+0x1ed/0x2a0
scsi_softirq_done+0x1c9/0x1d0
blk_done_softirq+0x181/0x1d0
__do_softirq+0xd9/0x57c
irq_exit+0xa2/0xc0
do_IRQ+0x8b/0x190
ret_from_intr+0x0/0x42
cpuidle_enter_state+0x15e/0x980
cpuidle_enter+0x69/0xc0
call_cpuidle+0x23/0x40
do_idle+0x248/0x280
cpu_startup_entry+0x1d/0x1f
start_secondary+0x1b2/0x230
secondary_startup_64+0xb6/0xc0
no locks held by swapper/22/0.
irq event stamp: 32871382
_raw_spin_unlock_irqrestore+0x53/0x60
_raw_spin_lock_irqsave+0x21/0x60
_local_bh_enable+0x21/0x30
irq_exit+0xa2/0xc0
read to 0xffff9f320a0a01d0 of 8 bytes by interrupt on cpu 2:
add_timer_randomness+0xe8/0x190
add_disk_randomness+0x85/0x280
scsi_end_request+0x43a/0x4a0
scsi_io_completion+0xb7/0x7e0
scsi_finish_command+0x1ed/0x2a0
scsi_softirq_done+0x1c9/0x1d0
blk_done_softirq+0x181/0x1d0
__do_softirq+0xd9/0x57c
irq_exit+0xa2/0xc0
do_IRQ+0x8b/0x190
ret_from_intr+0x0/0x42
cpuidle_enter_state+0x15e/0x980
cpuidle_enter+0x69/0xc0
call_cpuidle+0x23/0x40
do_idle+0x248/0x280
cpu_startup_entry+0x1d/0x1f
start_secondary+0x1b2/0x230
secondary_startup_64+0xb6/0xc0
no locks held by swapper/2/0.
irq event stamp: 37846304
_raw_spin_unlock_irqrestore+0x53/0x60
_raw_spin_lock_irqsave+0x21/0x60
_local_bh_enable+0x21/0x30
irq_exit+0xa2/0xc0
Reported by Kernel Concurrency Sanitizer on:
Hardware name: HP ProLiant BL660c Gen9, BIOS I38 10/17/2018
Link: https://lore.kernel.org/r/1582648024-13111-1-git-send-email-cai@lca.pw
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
1 file changed
