linux-kernel - [PATCH] dma: Fix a double free in dma_async_device

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Date:   Mon, 22 Mar 2021 06:08:36 -0700
From:   Lv Yunlong <lyl2019@...l.ustc.edu.cn>
To:     vkoul@...nel.org
Cc:     dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
        Lv Yunlong <lyl2019@...l.ustc.edu.cn>
Subject: [PATCH] dma: Fix a double free in dma_async_device_register

In dma_async_device_register, in the loop
list_for_each_entry(chan, &device->channels, device_node).
If __dma_async_device_channel_register(device, chan) failed
and it colud free chan->local and return err.

But in the err_out branch, it will free chan->local again.
My patch sets chan->local to NULL after it is freed in
__dma_async_device_channel_register().

Signed-off-by: Lv Yunlong <lyl2019@...l.ustc.edu.cn>
---
 drivers/dma/dmaengine.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index fe6a460c4373..af3ee288bc11 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -1086,6 +1086,7 @@ static int __dma_async_device_channel_register(struct dma_device *device,
 	kfree(chan->dev);
  err_free_local:
 	free_percpu(chan->local);
+	chan->local = NULL;
 	return rc;
 }

-- 
2.25.1