[PATCH v2] mhi: Fix double dma free

[PATCH v2] mhi: Fix double dma free

[Loic Poulain]

mhi_deinit_chan_ctxt functionthat takes care of unitializing channel
resources, including unmapping coherent MHI areas, can be called
from different path in case of controller unregistering/removal:
 - From a client driver remove callback, via mhi_unprepare_channel
 - From mhi_driver_remove that unitialize all channels

mhi_driver_remove()
|-> driver->remove()
|    |-> mhi_unprepare_channel()
|        |-> mhi_deinit_chan_ctxt()
|...
|-> mhi_deinit_chan_ctxt()

This leads to double dma freeing...

Fix that by preventing deinit for already uninitialized channel.

Fixes: a7f422f2f89e ("bus: mhi: Fix channel close issue on driver remove")
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Reported-by: Kalle Valo <kvalo@codeaurora.org>
Tested-by: Kalle Valo <kvalo@codeaurora.org>
---
 v2: add Fixes tag

 drivers/bus/mhi/core/init.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
index aa575d3..be4eebb 100644
--- a/drivers/bus/mhi/core/init.c
+++ b/drivers/bus/mhi/core/init.c
@@ -557,6 +557,9 @@ void mhi_deinit_chan_ctxt(struct mhi_controller *mhi_cntrl,
 	tre_ring = &mhi_chan->tre_ring;
 	chan_ctxt = &mhi_cntrl->mhi_ctxt->chan_ctxt[mhi_chan->chan];
 
+	if (!chan_ctxt->rbase) /* Already uninitialized */
+		return;
+
 	mhi_free_coherent(mhi_cntrl, tre_ring->alloc_size,
 			  tre_ring->pre_aligned, tre_ring->dma_handle);
 	vfree(buf_ring->base);
-- 
2.7.4

Re: [PATCH v2] mhi: Fix double dma free

[Manivannan Sadhasivam]

On Tue, Feb 09, 2021 at 07:11:04PM +0100, Loic Poulain wrote:
> mhi_deinit_chan_ctxt functionthat takes care of unitializing channel
> resources, including unmapping coherent MHI areas, can be called
> from different path in case of controller unregistering/removal:
>  - From a client driver remove callback, via mhi_unprepare_channel
>  - From mhi_driver_remove that unitialize all channels
> 
> mhi_driver_remove()
> |-> driver->remove()
> |    |-> mhi_unprepare_channel()
> |        |-> mhi_deinit_chan_ctxt()
> |...
> |-> mhi_deinit_chan_ctxt()
> 
> This leads to double dma freeing...
> 
> Fix that by preventing deinit for already uninitialized channel.
> 
> Fixes: a7f422f2f89e ("bus: mhi: Fix channel close issue on driver remove")
> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> Reported-by: Kalle Valo <kvalo@codeaurora.org>
> Tested-by: Kalle Valo <kvalo@codeaurora.org>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Thanks,
Mani

> ---
>  v2: add Fixes tag
> 
>  drivers/bus/mhi/core/init.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
> index aa575d3..be4eebb 100644
> --- a/drivers/bus/mhi/core/init.c
> +++ b/drivers/bus/mhi/core/init.c
> @@ -557,6 +557,9 @@ void mhi_deinit_chan_ctxt(struct mhi_controller *mhi_cntrl,
>  	tre_ring = &mhi_chan->tre_ring;
>  	chan_ctxt = &mhi_cntrl->mhi_ctxt->chan_ctxt[mhi_chan->chan];
>  
> +	if (!chan_ctxt->rbase) /* Already uninitialized */
> +		return;
> +
>  	mhi_free_coherent(mhi_cntrl, tre_ring->alloc_size,
>  			  tre_ring->pre_aligned, tre_ring->dma_handle);
>  	vfree(buf_ring->base);
> -- 
> 2.7.4
> 

Re: [PATCH v2] mhi: Fix double dma free

[patchwork-bot+linux-arm-msm]

Hello:

This patch was applied to qcom/linux.git (refs/heads/for-next):

On Tue,  9 Feb 2021 19:11:04 +0100 you wrote:
> mhi_deinit_chan_ctxt functionthat takes care of unitializing channel
> resources, including unmapping coherent MHI areas, can be called
> from different path in case of controller unregistering/removal:
>  - From a client driver remove callback, via mhi_unprepare_channel
>  - From mhi_driver_remove that unitialize all channels
> 
> mhi_driver_remove()
> |-> driver->remove()
> |    |-> mhi_unprepare_channel()
> |        |-> mhi_deinit_chan_ctxt()
> |...
> |-> mhi_deinit_chan_ctxt()
> 
> [...]

Here is the summary with links:
  - [v2] mhi: Fix double dma free
    https://git.kernel.org/qcom/c/db4e8de1935b

You are awesome, thank you!
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