diff options
author | Eric Dumazet <edumazet@google.com> | 2019-11-06 09:48:04 -0800 |
---|---|---|
committer | Thomas Gleixner <tglx@linutronix.de> | 2019-11-06 23:18:31 +0100 |
commit | 56144737e67329c9aaed15f942d46a6302e2e3d8 (patch) | |
tree | 78a548e91c20af76be898edf0840a5f4667a6800 | |
parent | 7252f1405df1634d798628847d87592de359fe47 (diff) | |
download | linux-56144737e67329c9aaed15f942d46a6302e2e3d8.tar.bz2 |
hrtimer: Annotate lockless access to timer->state
syzbot reported various data-race caused by hrtimer_is_queued() reading
timer->state. A READ_ONCE() is required there to silence the warning.
Also add the corresponding WRITE_ONCE() when timer->state is set.
In remove_hrtimer() the hrtimer_is_queued() helper is open coded to avoid
loading timer->state twice.
KCSAN reported these cases:
BUG: KCSAN: data-race in __remove_hrtimer / tcp_pacing_check
write to 0xffff8880b2a7d388 of 1 bytes by interrupt on cpu 0:
__remove_hrtimer+0x52/0x130 kernel/time/hrtimer.c:991
__run_hrtimer kernel/time/hrtimer.c:1496 [inline]
__hrtimer_run_queues+0x250/0x600 kernel/time/hrtimer.c:1576
hrtimer_run_softirq+0x10e/0x150 kernel/time/hrtimer.c:1593
__do_softirq+0x115/0x33f kernel/softirq.c:292
run_ksoftirqd+0x46/0x60 kernel/softirq.c:603
smpboot_thread_fn+0x37d/0x4a0 kernel/smpboot.c:165
kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352
read to 0xffff8880b2a7d388 of 1 bytes by task 24652 on cpu 1:
tcp_pacing_check net/ipv4/tcp_output.c:2235 [inline]
tcp_pacing_check+0xba/0x130 net/ipv4/tcp_output.c:2225
tcp_xmit_retransmit_queue+0x32c/0x5a0 net/ipv4/tcp_output.c:3044
tcp_xmit_recovery+0x7c/0x120 net/ipv4/tcp_input.c:3558
tcp_ack+0x17b6/0x3170 net/ipv4/tcp_input.c:3717
tcp_rcv_established+0x37e/0xf50 net/ipv4/tcp_input.c:5696
tcp_v4_do_rcv+0x381/0x4e0 net/ipv4/tcp_ipv4.c:1561
sk_backlog_rcv include/net/sock.h:945 [inline]
__release_sock+0x135/0x1e0 net/core/sock.c:2435
release_sock+0x61/0x160 net/core/sock.c:2951
sk_stream_wait_memory+0x3d7/0x7c0 net/core/stream.c:145
tcp_sendmsg_locked+0xb47/0x1f30 net/ipv4/tcp.c:1393
tcp_sendmsg+0x39/0x60 net/ipv4/tcp.c:1434
inet_sendmsg+0x6d/0x90 net/ipv4/af_inet.c:807
sock_sendmsg_nosec net/socket.c:637 [inline]
sock_sendmsg+0x9f/0xc0 net/socket.c:657
BUG: KCSAN: data-race in __remove_hrtimer / __tcp_ack_snd_check
write to 0xffff8880a3a65588 of 1 bytes by interrupt on cpu 0:
__remove_hrtimer+0x52/0x130 kernel/time/hrtimer.c:991
__run_hrtimer kernel/time/hrtimer.c:1496 [inline]
__hrtimer_run_queues+0x250/0x600 kernel/time/hrtimer.c:1576
hrtimer_run_softirq+0x10e/0x150 kernel/time/hrtimer.c:1593
__do_softirq+0x115/0x33f kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0xbb/0xe0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0xe6/0x280 arch/x86/kernel/apic/apic.c:1137
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
read to 0xffff8880a3a65588 of 1 bytes by task 22891 on cpu 1:
__tcp_ack_snd_check+0x415/0x4f0 net/ipv4/tcp_input.c:5265
tcp_ack_snd_check net/ipv4/tcp_input.c:5287 [inline]
tcp_rcv_established+0x750/0xf50 net/ipv4/tcp_input.c:5708
tcp_v4_do_rcv+0x381/0x4e0 net/ipv4/tcp_ipv4.c:1561
sk_backlog_rcv include/net/sock.h:945 [inline]
__release_sock+0x135/0x1e0 net/core/sock.c:2435
release_sock+0x61/0x160 net/core/sock.c:2951
sk_stream_wait_memory+0x3d7/0x7c0 net/core/stream.c:145
tcp_sendmsg_locked+0xb47/0x1f30 net/ipv4/tcp.c:1393
tcp_sendmsg+0x39/0x60 net/ipv4/tcp.c:1434
inet_sendmsg+0x6d/0x90 net/ipv4/af_inet.c:807
sock_sendmsg_nosec net/socket.c:637 [inline]
sock_sendmsg+0x9f/0xc0 net/socket.c:657
__sys_sendto+0x21f/0x320 net/socket.c:1952
__do_sys_sendto net/socket.c:1964 [inline]
__se_sys_sendto net/socket.c:1960 [inline]
__x64_sys_sendto+0x89/0xb0 net/socket.c:1960
do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 24652 Comm: syz-executor.3 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[ tglx: Added comments ]
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191106174804.74723-1-edumazet@google.com
-rw-r--r-- | include/linux/hrtimer.h | 14 | ||||
-rw-r--r-- | kernel/time/hrtimer.c | 11 |
2 files changed, 17 insertions, 8 deletions
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 1b9a51a1bccb..1f98b52118f0 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -456,12 +456,18 @@ extern u64 hrtimer_next_event_without(const struct hrtimer *exclude); extern bool hrtimer_active(const struct hrtimer *timer); -/* - * Helper function to check, whether the timer is on one of the queues +/** + * hrtimer_is_queued = check, whether the timer is on one of the queues + * @timer: Timer to check + * + * Returns: True if the timer is queued, false otherwise + * + * The function can be used lockless, but it gives only a current snapshot. */ -static inline int hrtimer_is_queued(struct hrtimer *timer) +static inline bool hrtimer_is_queued(struct hrtimer *timer) { - return timer->state & HRTIMER_STATE_ENQUEUED; + /* The READ_ONCE pairs with the update functions of timer->state */ + return !!(READ_ONCE(timer->state) & HRTIMER_STATE_ENQUEUED); } /* diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 65605530ee34..7f31932216a1 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -966,7 +966,8 @@ static int enqueue_hrtimer(struct hrtimer *timer, base->cpu_base->active_bases |= 1 << base->index; - timer->state = HRTIMER_STATE_ENQUEUED; + /* Pairs with the lockless read in hrtimer_is_queued() */ + WRITE_ONCE(timer->state, HRTIMER_STATE_ENQUEUED); return timerqueue_add(&base->active, &timer->node); } @@ -988,7 +989,8 @@ static void __remove_hrtimer(struct hrtimer *timer, struct hrtimer_cpu_base *cpu_base = base->cpu_base; u8 state = timer->state; - timer->state = newstate; + /* Pairs with the lockless read in hrtimer_is_queued() */ + WRITE_ONCE(timer->state, newstate); if (!(state & HRTIMER_STATE_ENQUEUED)) return; @@ -1013,8 +1015,9 @@ static void __remove_hrtimer(struct hrtimer *timer, static inline int remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, bool restart) { - if (hrtimer_is_queued(timer)) { - u8 state = timer->state; + u8 state = timer->state; + + if (state & HRTIMER_STATE_ENQUEUED) { int reprogram; /* |