[PATCH] mtk-sd: Prevent memory corruption from DMA map failure

[Sergey Senozhatsky]

On (25/06/25 12:56), Sergey Senozhatsky wrote:
> On (25/06/12 20:26), Masami Hiramatsu (Google) wrote:
> [..]
> > @@ -1466,8 +1471,18 @@ static void msdc_ops_request(struct mmc_host *mmc, struct mmc_request *mrq)
> >  	WARN_ON(!host->hsq_en && host->mrq);
> >  	host->mrq = mrq;
> >  
> > -	if (mrq->data)
> > +	if (mrq->data) {
> >  		msdc_prepare_data(host, mrq->data);
> > +		if (!msdc_data_prepared(mrq->data)) {
> > +			/*
> > +			 * Failed to prepare DMA area, fail fast before
> > +			 * starting any commands.
> > +			 */
> > +			mrq->cmd->error = -ENOSPC;
> > +			mmc_request_done(mmc_from_priv(host), mrq);
> 
> Do we end up having a stale/dangling host->mrq pointer here?

Something like this maybe?

---

diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
index b12cfb9a5e5f..46bb770ace41 100644
--- a/drivers/mmc/host/mtk-sd.c
+++ b/drivers/mmc/host/mtk-sd.c
@@ -1498,6 +1498,7 @@ static void msdc_ops_request(struct mmc_host *mmc, struct mmc_request *mrq)
 			 */
 			mrq->cmd->error = -ENOSPC;
 			mmc_request_done(mmc_from_priv(host), mrq);
+			host->mrq = NULL;
 			return;
 		}
 	}