diff options
| -rw-r--r-- | lib/Kconfig.kfence | 1 | ||||
| -rw-r--r-- | mm/kfence/core.c | 45 |
2 files changed, 30 insertions, 16 deletions
diff --git a/lib/Kconfig.kfence b/lib/Kconfig.kfence index 78f50ccb3b45..e641add33947 100644 --- a/lib/Kconfig.kfence +++ b/lib/Kconfig.kfence @@ -7,6 +7,7 @@ menuconfig KFENCE bool "KFENCE: low-overhead sampling-based memory safety error detector" depends on HAVE_ARCH_KFENCE && (SLAB || SLUB) select STACKTRACE + select IRQ_WORK help KFENCE is a low-overhead sampling-based detector of heap out-of-bounds access, use-after-free, and invalid-free errors. KFENCE is designed diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 768dbd58170d..235d726f88bc 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -10,6 +10,7 @@ #include <linux/atomic.h> #include <linux/bug.h> #include <linux/debugfs.h> +#include <linux/irq_work.h> #include <linux/kcsan-checks.h> #include <linux/kfence.h> #include <linux/kmemleak.h> @@ -587,6 +588,17 @@ late_initcall(kfence_debugfs_init); /* === Allocation Gate Timer ================================================ */ +#ifdef CONFIG_KFENCE_STATIC_KEYS +/* Wait queue to wake up allocation-gate timer task. */ +static DECLARE_WAIT_QUEUE_HEAD(allocation_wait); + +static void wake_up_kfence_timer(struct irq_work *work) +{ + wake_up(&allocation_wait); +} +static DEFINE_IRQ_WORK(wake_up_kfence_timer_work, wake_up_kfence_timer); +#endif + /* * Set up delayed work, which will enable and disable the static key. We need to * use a work queue (rather than a simple timer), since enabling and disabling a @@ -604,25 +616,13 @@ static void toggle_allocation_gate(struct work_struct *work) if (!READ_ONCE(kfence_enabled)) return; - /* Enable static key, and await allocation to happen. */ atomic_set(&kfence_allocation_gate, 0); #ifdef CONFIG_KFENCE_STATIC_KEYS + /* Enable static key, and await allocation to happen. */ static_branch_enable(&kfence_allocation_key); - /* - * Await an allocation. Timeout after 1 second, in case the kernel stops - * doing allocations, to avoid stalling this worker task for too long. - */ - { - unsigned long end_wait = jiffies + HZ; - - do { - set_current_state(TASK_UNINTERRUPTIBLE); - if (atomic_read(&kfence_allocation_gate) != 0) - break; - schedule_timeout(1); - } while (time_before(jiffies, end_wait)); - __set_current_state(TASK_RUNNING); - } + + wait_event_timeout(allocation_wait, atomic_read(&kfence_allocation_gate), HZ); + /* Disable static key and reset timer. */ static_branch_disable(&kfence_allocation_key); #endif @@ -729,6 +729,19 @@ void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags) */ if (atomic_read(&kfence_allocation_gate) || atomic_inc_return(&kfence_allocation_gate) > 1) return NULL; +#ifdef CONFIG_KFENCE_STATIC_KEYS + /* + * waitqueue_active() is fully ordered after the update of + * kfence_allocation_gate per atomic_inc_return(). + */ + if (waitqueue_active(&allocation_wait)) { + /* + * Calling wake_up() here may deadlock when allocations happen + * from within timer code. Use an irq_work to defer it. + */ + irq_work_queue(&wake_up_kfence_timer_work); + } +#endif if (!READ_ONCE(kfence_enabled)) return NULL; |