From ea45b6008f8095db0cc09ad6e03c7785c2986197 Mon Sep 17 00:00:00 2001
From: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Date: Tue, 30 Mar 2021 18:44:58 -0700
Subject: [PATCH] dmaengine: Fix a double free in dma_async_device_register
Git-commit: ea45b6008f8095db0cc09ad6e03c7785c2986197
Patch-mainline: v5.12
References: git-fixes

In the first list_for_each_entry() macro of dma_async_device_register,
it gets the chan from list and calls __dma_async_device_channel_register
(..,chan). We can see that chan->local is allocated by alloc_percpu() and
it is freed chan->local by free_percpu(chan->local) when
__dma_async_device_channel_register() failed.

But after __dma_async_device_channel_register() failed, the caller will
goto err_out and freed the chan->local in the second time by free_percpu().

The cause of this problem is forget to set chan->local to NULL when
chan->local was freed in __dma_async_device_channel_register(). My
patch sets chan->local to NULL when the callee failed to avoid double free.

Fixes: d2fb0a0438384 ("dmaengine: break out channel registration")
Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/20210331014458.3944-1-lyl2019@mail.ustc.edu.cn
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 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;
 }
 
-- 
2.26.2