linux-kernel - Re: [PATCH] [RESEND] devres: Fix possible use after free

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Date:	Wed, 15 Jun 2011 20:14:19 +0300
From:	Maxin B John <maxin.john@...il.com>
To:	akpm@...ux-foundation.org
Cc:	tj@...nel.org, eike-kernel@...tec.de, segooon@...il.com,
	tglx@...utronix.de, linux-kernel@...r.kernel.org, jkosina@...e.cz
Subject: Re: [PATCH] [RESEND] devres: Fix possible use after free

devres uses the pointer value as key after it's freed, which is safe but 
triggers spurious use-after-free warnings on some static analysis tools. 
Rearrange code to avoid such warnings.

Signed-off-by: Maxin B. John <maxin.john@...il.com>
Reviewed-by: Rolf Eike Beer <eike-kernel@...tec.de>
Acked-by: Tejun Heo <tj@...nel.org>
---
diff --git a/kernel/irq/devres.c b/kernel/irq/devres.c
index 1ef4ffc..bd8e788 100644
--- a/kernel/irq/devres.c
+++ b/kernel/irq/devres.c
@@ -87,8 +87,8 @@ void devm_free_irq(struct device *dev, unsigned int irq, void *dev_id)
 {
 	struct irq_devres match_data = { irq, dev_id };
 
-	free_irq(irq, dev_id);
 	WARN_ON(devres_destroy(dev, devm_irq_release, devm_irq_match,
 			       &match_data));
+	free_irq(irq, dev_id);
 }
 EXPORT_SYMBOL(devm_free_irq);
diff --git a/lib/devres.c b/lib/devres.c
index 6efddf5..7c0e953 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -79,9 +79,9 @@ EXPORT_SYMBOL(devm_ioremap_nocache);
  */
 void devm_iounmap(struct device *dev, void __iomem *addr)
 {
-	iounmap(addr);
 	WARN_ON(devres_destroy(dev, devm_ioremap_release, devm_ioremap_match,
 			       (void *)addr));
+	iounmap(addr);
 }
 EXPORT_SYMBOL(devm_iounmap);
 
diff --git a/mm/dmapool.c b/mm/dmapool.c
index 03bf3bb..fbb58e3 100644
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -500,7 +500,7 @@ void dmam_pool_destroy(struct dma_pool *pool)
 {
 	struct device *dev = pool->dev;
 
-	dma_pool_destroy(pool);
 	WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
+	dma_pool_destroy(pool);
 }
 EXPORT_SYMBOL(dmam_pool_destroy);
--
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