linux-kernel - Re: [PATCH] workqueue: fix null-ptr-deref on __alloc

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Message-ID: <20240815072427.GC12106@google.com>
Date: Thu, 15 Aug 2024 16:24:27 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Matthew Brost <matthew.brost@...el.com>
Cc: Tejun Heo <tj@...nel.org>, Lai Jiangshan <jiangshanlai@...il.com>,
	linux-kernel@...r.kernel.org,
	Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: Re: [PATCH] workqueue: fix null-ptr-deref on __alloc_workqueue()
 error

On (24/08/15 16:09), Sergey Senozhatsky wrote:
> On (24/08/15 16:02), Sergey Senozhatsky wrote:
> Oh, okay, so this is related to [1]
> 
> 	workqueue: Split alloc_workqueue into internal function and lockdep init
> 
> Cc-ing Matthew on this.
> 
> [1] https://lore.kernel.org/all/20240809222827.3211998-2-matthew.brost@intel.com/

Matthew, did you mean to do something like below instead?
Otherwise it breaks boot for me.

---

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 7a2f4cbbe8b2..55e0e69ee604 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -5615,12 +5615,11 @@ static void wq_adjust_max_active(struct workqueue_struct *wq)
 	} while (activated);
 }
 
-__printf(1, 4)
 static struct workqueue_struct *__alloc_workqueue(const char *fmt,
 						  unsigned int flags,
-						  int max_active, ...)
+						  int max_active,
+						  va_list args)
 {
-	va_list args;
 	struct workqueue_struct *wq;
 	size_t wq_size;
 	int name_len;
@@ -5652,9 +5651,7 @@ static struct workqueue_struct *__alloc_workqueue(const char *fmt,
 			goto err_free_wq;
 	}
 
-	va_start(args, max_active);
 	name_len = vsnprintf(wq->name, sizeof(wq->name), fmt, args);
-	va_end(args);
 
 	if (name_len >= WQ_NAME_LEN)
 		pr_warn_once("workqueue: name exceeds WQ_NAME_LEN. Truncating to: %s\n",