Messages in this thread Patch in this message | | | From | Guoyong Wang <> | Subject | [PATCH] random: Fix the issue of '_might_sleep' function running in an atomic contex | Date | Mon, 18 Mar 2024 15:53:27 +0800 |
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'input_handle_event' runs in an atomic context (spinlock). In rare instances, it may call the '_might_sleep' function, which could trigger a kernel exception.
Backtrace: [<ffffffd613025ba0>] die+0xa8/0x2fc [<ffffffd613027428>] bug_handler+0x44/0xec [<ffffffd613016964>] brk_handler+0x90/0x144 [<ffffffd613041e58>] do_debug_exception+0xa0/0x148 [<ffffffd61400c208>] el1_dbg+0x60/0x7c [<ffffffd61400c000>] el1h_64_sync_handler+0x38/0x90 [<ffffffd613011294>] el1h_64_sync+0x64/0x6c [<ffffffd613102d88>] __might_resched+0x1fc/0x2e8 [<ffffffd613102b54>] __might_sleep+0x44/0x7c [<ffffffd6130b6eac>] cpus_read_lock+0x1c/0xec [<ffffffd6132c2820>] static_key_enable+0x14/0x38 [<ffffffd61400ac08>] crng_set_ready+0x14/0x28 [<ffffffd6130df4dc>] execute_in_process_context+0xb8/0xf8 [<ffffffd61400ab30>] _credit_init_bits+0x118/0x1dc [<ffffffd6138580c8>] add_timer_randomness+0x264/0x270 [<ffffffd613857e54>] add_input_randomness+0x38/0x48 [<ffffffd613a80f94>] input_handle_event+0x2b8/0x490 [<ffffffd613a81310>] input_event+0x6c/0x98
Signed-off-by: Guoyong Wang <guoyong.wang@mediatek.com> --- drivers/char/random.c | 2 +- include/linux/workqueue.h | 1 + kernel/workqueue.c | 26 ++++++++++++++++++++++++++ 3 files changed, 28 insertions(+), 1 deletion(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c index 456be28ba67c..00be9426a6fc 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -719,7 +719,7 @@ static void __cold _credit_init_bits(size_t bits) if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) { crng_reseed(NULL); /* Sets crng_init to CRNG_READY under base_crng.lock. */ if (static_key_initialized) - execute_in_process_context(crng_set_ready, &set_ready); + execute_in_non_atomic_context(crng_set_ready, &set_ready); atomic_notifier_call_chain(&random_ready_notifier, 0, NULL); wake_up_interruptible(&crng_init_wait); kill_fasync(&fasync, SIGIO, POLL_IN); diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 158784dd189a..eb17c62d23aa 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -550,6 +550,7 @@ extern void drain_workqueue(struct workqueue_struct *wq); extern int schedule_on_each_cpu(work_func_t func); int execute_in_process_context(work_func_t fn, struct execute_work *); +int execute_in_non_atomic_context(work_func_t fn, struct execute_work *ew); extern bool flush_work(struct work_struct *work); extern bool cancel_work(struct work_struct *work); diff --git a/kernel/workqueue.c b/kernel/workqueue.c index bf2bdac46843..8f212346da7a 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -4449,6 +4449,32 @@ int execute_in_process_context(work_func_t fn, struct execute_work *ew) } EXPORT_SYMBOL_GPL(execute_in_process_context); +/** + * execute_in_non_atomic_context - reliably execute the routine with user context + * @fn: the function to execute + * @ew: guaranteed storage for the execute work structure (must + * be available when the work executes) + * + * Schedules the function for delayed execution if atomic context is available, + * otherwise executes the function immediately . + * + * Return: 0 - function was executed + * 1 - function was scheduled for execution + */ +int execute_in_non_atomic_context(work_func_t fn, struct execute_work *ew) +{ + if (!in_atomic()) { + fn(&ew->work); + return 0; + } + + INIT_WORK(&ew->work, fn); + schedule_work(&ew->work); + + return 1; +} +EXPORT_SYMBOL_GPL(execute_in_non_atomic_context); + /** * free_workqueue_attrs - free a workqueue_attrs * @attrs: workqueue_attrs to free -- 2.18.0
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