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MHI EP stack makes use of the MHI controller drivers like MHI EPF to do read/write to the host memory. And that driver is free to use mechanisms like DMA to offload the read/write operations. So if DMA is used for offload, then there is no guarantee that those DMA operations would be completed by the time mhi_ep_remove() gets called. This can lead to UAF (Use-After-Free) issues as the DMA callback can trigger xfer_cb() even after mhi_ep_remove() has returned. So to fix this issue, introduce the mhi_cntrl->flush_async() callback and call it in mhi_ep_remove() to drain all the in-flight async transfers before disconnecting the channels. The completion handlers keep triggering xfer_cb() as long as it is set. So flushing the transfers after notifying the client about the disconnect (-ENOTCONN) would still let a success callback slip through afterwards and lead to the same UAF. So disable the channels first to prevent new transfers, then flush the in-flight transfers so that their completions are delivered while xfer_cb() is still valid and only then notify the disconnect and clear xfer_cb(). Fixes:2547beb00d("bus: mhi: ep: Add support for async DMA read operation") Fixes:ee08acb58f("bus: mhi: ep: Add support for async DMA write operation") Reviewed-by: Frank Li <Frank.Li@nxp.com> Cc: stable+noautosel@kernel.org # Needs dmaengine driver fix as well Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>