Re: [PATCH v2] dma: Fix a double free in dma_async_device_register
From: Dave Jiang <dave.jiang@intel.com>
Date: 2021-03-31 02:49:41
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On 3/30/2021 6:44 PM, Lv Yunlong wrote:
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 <redacted>Reviewed-by: Dave Jiang <dave.jiang@intel.com>
quoted hunk ↗ jump to hunk
--- 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; }