From 4310c6b8e75d6a47f7548e5948fbe6318aa4440a Mon Sep 17 00:00:00 2001 From: Fedor Pchelkin Date: Mon, 31 Aug 2026 10:58:09 +0300 Subject: thunderbolt: Fix NULL dereference in tb_remove_work() There is a slight race between tb_remove_work() and tb_domain_remove() which leads to dereferencing a NULL tb->root_switch pointer inside tb_free_unplugged_xdomains(): Thread A Thread B tb_remove_work() tb_domain_remove() mutex_lock(&tb->lock) tb_stop() /* doesn't cancel a running callback */ cancel_delayed_work(&tcm->remove_work) ... tb_switch_remove(tb->root_switch) tb->root_switch = NULL mutex_unlock(&tb->lock) mutex_lock(&tb->lock) ... /* without checking ->root_switch */ tb_free_unplugged_xdomains(tb->root_switch) mutex_unlock(&tb->lock) Commit a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without holding tb->lock") doesn't seem right to move tb_free_unplugged_xdomains() out of the &tb->lock section and the check for tb->root_switch, in particular. It states: For this reason separate removing the XDomain from the topology data structures (where we need the lock) from unregistering the device from the bus (where remove callbacks of the drivers are being called). tb_free_unplugged_xdomains() belongs to the former group of functions requiring the lock. And it also calls tb_xdomain_remove() which should only be called with &tb->lock held. Found by Linux Verification Center (linuxtesting.org) with Svace static analysis tool. Fixes: a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without holding tb->lock") Cc: stable@vger.kernel.org Signed-off-by: Fedor Pchelkin Signed-off-by: Mika Westerberg --- drivers/clocksource/timer-msc313e.c | 253 ++++++++++++++++++++++++++++++++++++ 1 file changed, 253 insertions(+) create mode 100644 drivers/clocksource/timer-msc313e.c (limited to 'drivers/clocksource/timer-msc313e.c') diff --git a/drivers/clocksource/timer-msc313e.c b/drivers/clocksource/timer-msc313e.c new file mode 100644 index 000000000..e4b9e3f16 --- /dev/null +++ b/drivers/clocksource/timer-msc313e.c @@ -0,0 +1,253 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * MStar timer driver + * + * Copyright (C) 2021 Daniel Palmer + * Copyright (C) 2021 Romain Perier + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#ifdef CONFIG_ARM +#include +#endif + +#include "timer-of.h" + +#define TIMER_NAME "msc313e_timer" + +#define MSC313E_REG_CTRL 0x00 +#define MSC313E_REG_CTRL_TIMER_EN BIT(0) +#define MSC313E_REG_CTRL_TIMER_TRIG BIT(1) +#define MSC313E_REG_CTRL_TIMER_INT_EN BIT(8) +#define MSC313E_REG_TIMER_MAX_LOW 0x08 +#define MSC313E_REG_TIMER_MAX_HIGH 0x0c +#define MSC313E_REG_COUNTER_LOW 0x10 +#define MSC313E_REG_COUNTER_HIGH 0x14 +#define MSC313E_REG_TIMER_DIVIDE 0x18 + +#define MSC313E_CLK_DIVIDER 9 +#define TIMER_SYNC_TICKS 3 + +#ifdef CONFIG_ARM +struct msc313e_delay { + void __iomem *base; + struct delay_timer delay; +}; +static struct msc313e_delay msc313e_delay; +#endif + +static void __iomem *msc313e_clksrc; + +static void msc313e_timer_stop(void __iomem *base) +{ + writew(0, base + MSC313E_REG_CTRL); +} + +static void msc313e_timer_start(void __iomem *base, bool periodic) +{ + u16 reg; + + reg = readw(base + MSC313E_REG_CTRL); + if (periodic) + reg |= MSC313E_REG_CTRL_TIMER_EN; + else + reg |= MSC313E_REG_CTRL_TIMER_TRIG; + writew(reg | MSC313E_REG_CTRL_TIMER_INT_EN, base + MSC313E_REG_CTRL); +} + +static void msc313e_timer_setup(void __iomem *base, unsigned long delay) +{ + unsigned long flags; + + local_irq_save(flags); + writew(delay >> 16, base + MSC313E_REG_TIMER_MAX_HIGH); + writew(delay & 0xffff, base + MSC313E_REG_TIMER_MAX_LOW); + local_irq_restore(flags); +} + +static unsigned long msc313e_timer_current_value(void __iomem *base) +{ + unsigned long flags; + u16 l, h; + + local_irq_save(flags); + l = readw(base + MSC313E_REG_COUNTER_LOW); + h = readw(base + MSC313E_REG_COUNTER_HIGH); + local_irq_restore(flags); + + return (((u32)h) << 16 | l); +} + +static int msc313e_timer_clkevt_shutdown(struct clock_event_device *evt) +{ + struct timer_of *timer = to_timer_of(evt); + + msc313e_timer_stop(timer_of_base(timer)); + + return 0; +} + +static int msc313e_timer_clkevt_set_oneshot(struct clock_event_device *evt) +{ + struct timer_of *timer = to_timer_of(evt); + + msc313e_timer_stop(timer_of_base(timer)); + msc313e_timer_start(timer_of_base(timer), false); + + return 0; +} + +static int msc313e_timer_clkevt_set_periodic(struct clock_event_device *evt) +{ + struct timer_of *timer = to_timer_of(evt); + + msc313e_timer_stop(timer_of_base(timer)); + msc313e_timer_setup(timer_of_base(timer), timer_of_period(timer)); + msc313e_timer_start(timer_of_base(timer), true); + + return 0; +} + +static int msc313e_timer_clkevt_next_event(unsigned long evt, struct clock_event_device *clkevt) +{ + struct timer_of *timer = to_timer_of(clkevt); + + msc313e_timer_stop(timer_of_base(timer)); + msc313e_timer_setup(timer_of_base(timer), evt); + msc313e_timer_start(timer_of_base(timer), false); + + return 0; +} + +static irqreturn_t msc313e_timer_clkevt_irq(int irq, void *dev_id) +{ + struct clock_event_device *evt = dev_id; + + evt->event_handler(evt); + + return IRQ_HANDLED; +} + +static u64 msc313e_timer_clksrc_read(struct clocksource *cs) +{ + return msc313e_timer_current_value(msc313e_clksrc) & cs->mask; +} + +#ifdef CONFIG_ARM +static unsigned long msc313e_read_delay_timer_read(void) +{ + return msc313e_timer_current_value(msc313e_delay.base); +} +#endif + +static u64 msc313e_timer_sched_clock_read(void) +{ + return msc313e_timer_current_value(msc313e_clksrc); +} + +static struct clock_event_device msc313e_clkevt = { + .name = TIMER_NAME, + .rating = 300, + .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, + .set_state_shutdown = msc313e_timer_clkevt_shutdown, + .set_state_periodic = msc313e_timer_clkevt_set_periodic, + .set_state_oneshot = msc313e_timer_clkevt_set_oneshot, + .tick_resume = msc313e_timer_clkevt_shutdown, + .set_next_event = msc313e_timer_clkevt_next_event, +}; + +static int __init msc313e_clkevt_init(struct device_node *np) +{ + int ret; + struct timer_of *to; + + to = kzalloc_obj(*to); + if (!to) + return -ENOMEM; + + to->flags = TIMER_OF_IRQ | TIMER_OF_CLOCK | TIMER_OF_BASE; + to->of_irq.handler = msc313e_timer_clkevt_irq; + ret = timer_of_init(np, to); + if (ret) + return ret; + + if (of_device_is_compatible(np, "sstar,ssd20xd-timer")) { + to->of_clk.rate = clk_get_rate(to->of_clk.clk) / MSC313E_CLK_DIVIDER; + to->of_clk.period = DIV_ROUND_UP(to->of_clk.rate, HZ); + writew(MSC313E_CLK_DIVIDER - 1, timer_of_base(to) + MSC313E_REG_TIMER_DIVIDE); + } + + msc313e_clkevt.cpumask = cpu_possible_mask; + msc313e_clkevt.irq = to->of_irq.irq; + to->clkevt = msc313e_clkevt; + + clockevents_config_and_register(&to->clkevt, timer_of_rate(to), + TIMER_SYNC_TICKS, 0xffffffff); + return 0; +} + +static int __init msc313e_clksrc_init(struct device_node *np) +{ + struct timer_of to = { 0 }; + int ret; + u16 reg; + + to.flags = TIMER_OF_BASE | TIMER_OF_CLOCK; + ret = timer_of_init(np, &to); + if (ret) + return ret; + + msc313e_clksrc = timer_of_base(&to); + reg = readw(msc313e_clksrc + MSC313E_REG_CTRL); + reg |= MSC313E_REG_CTRL_TIMER_EN; + writew(reg, msc313e_clksrc + MSC313E_REG_CTRL); + +#ifdef CONFIG_ARM + msc313e_delay.base = timer_of_base(&to); + msc313e_delay.delay.read_current_timer = msc313e_read_delay_timer_read; + msc313e_delay.delay.freq = timer_of_rate(&to); + + register_current_timer_delay(&msc313e_delay.delay); +#endif + + sched_clock_register(msc313e_timer_sched_clock_read, 32, timer_of_rate(&to)); + return clocksource_mmio_init(timer_of_base(&to), TIMER_NAME, timer_of_rate(&to), 300, 32, + msc313e_timer_clksrc_read); +} + +static int __init msc313e_timer_init(struct device_node *np) +{ + int ret = 0; + static int num_called; + + switch (num_called) { + case 0: + ret = msc313e_clksrc_init(np); + if (ret) + return ret; + break; + + default: + ret = msc313e_clkevt_init(np); + if (ret) + return ret; + break; + } + + num_called++; + + return 0; +} + +TIMER_OF_DECLARE(msc313, "mstar,msc313e-timer", msc313e_timer_init); +TIMER_OF_DECLARE(ssd20xd, "sstar,ssd20xd-timer", msc313e_timer_init); -- cgit v1.3.1