This is a note to let you know that I've just added the patch titled dmaengine: Fix a double free in dma_async_device_register to the 5.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: dmaengine-fix-a-double-free-in-dma_async_device_regi.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 3aae7d2464ebfdeea75fbbe203bc9f77847b6d53 Author: Lv Yunlong <lyl2019@xxxxxxxxxxxxxxxx> Date: Tue Mar 30 18:44:58 2021 -0700 dmaengine: Fix a double free in dma_async_device_register [ Upstream commit ea45b6008f8095db0cc09ad6e03c7785c2986197 ] 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@xxxxxxxxxxxxxxxx> Reviewed-by: Dave Jiang <dave.jiang@xxxxxxxxx> Link: https://lore.kernel.org/r/20210331014458.3944-1-lyl2019@xxxxxxxxxxxxxxxx Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> 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; }