From 0de4cb473aed57ee4ba7e0551ad27bddc19fc519 Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Tue, 28 Apr 2026 08:10:43 -0700 Subject: workqueue: fix devm_alloc_workqueue() va_list misuse devm_alloc_workqueue() built a va_list and passed it as a single positional argument to the variadic alloc_workqueue() macro: va_start(args, max_active); wq = alloc_workqueue(fmt, flags, max_active, args); va_end(args); C does not allow forwarding a va_list through a ... parameter. alloc_workqueue() expands to alloc_workqueue_noprof(), which runs its own va_start() over its ... params, so the inner vsnprintf(wq->name, sizeof(wq->name), fmt, args) in __alloc_workqueue() received the outer va_list object as the first variadic slot rather than the caller's actual format arguments. Add a new static helper alloc_workqueue_va() that wraps __alloc_workqueue() and runs wq_init_lockdep() on success, and fold both alloc_workqueue_noprof() and devm_alloc_workqueue_noprof() onto it as suggested by Tejun. The wq_init_lockdep() step is required on the devm path too, otherwise __flush_workqueue()'s on-stack COMPLETION_INITIALIZER_ONSTACK_MAP would NULL-deref wq->lockdep_map. No caller changes are required. devm_alloc_ordered_workqueue() is a macro forwarding to devm_alloc_workqueue() and inherits the fix. Two in-tree callers actively trigger the broken path on every probe: drivers/power/supply/mt6370-charger.c:889 drivers/power/supply/max77705_charger.c:649 both of which use devm_alloc_ordered_workqueue(dev, "%s", 0, dev_name(dev)). A standalone reproducer module is available at[1]. Link: https://github.com/leitao/debug/blob/main/workqueue/valist/wq_va_test.c [1] Fixes: 1dfc9d60a69e ("workqueue: devres: Add device-managed allocate workqueue") Signed-off-by: Breno Leitao Signed-off-by: Tejun Heo --- include/linux/workqueue.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index ab6cb70ca1a5..6177624539b3 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -534,8 +534,10 @@ alloc_workqueue_noprof(const char *fmt, unsigned int flags, int max_active, ...) * Pointer to the allocated workqueue on success, %NULL on failure. */ __printf(2, 5) struct workqueue_struct * -devm_alloc_workqueue(struct device *dev, const char *fmt, unsigned int flags, - int max_active, ...); +devm_alloc_workqueue_noprof(struct device *dev, const char *fmt, + unsigned int flags, int max_active, ...); +#define devm_alloc_workqueue(...) \ + alloc_hooks(devm_alloc_workqueue_noprof(__VA_ARGS__)) #ifdef CONFIG_LOCKDEP /** -- cgit v1.2.3