The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x f5de469990f19569627ea0dd56536ff5a13beaa3 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025070635-mockup-amicably-51ad@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f5de469990f19569627ea0dd56536ff5a13beaa3 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" mhiramat@kernel.org Date: Thu, 12 Jun 2025 20:26:10 +0900 Subject: [PATCH] mtk-sd: Prevent memory corruption from DMA map failure

If msdc_prepare_data() fails to map the DMA region, the request is not prepared for data receiving, but msdc_start_data() proceeds the DMA with previous setting. Since this will lead a memory corruption, we have to stop the request operation soon after the msdc_prepare_data() fails to prepare it.

Signed-off-by: Masami Hiramatsu (Google) mhiramat@kernel.org Fixes: 208489032bdd ("mmc: mediatek: Add Mediatek MMC driver") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/174972756982.3337526.6755001617701603082.stgit@mhi... Signed-off-by: Ulf Hansson ulf.hansson@linaro.org

diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c index b1d1586cf1fc..b12cfb9a5e5f 100644 --- a/drivers/mmc/host/mtk-sd.c +++ b/drivers/mmc/host/mtk-sd.c @@ -853,6 +853,11 @@ static void msdc_prepare_data(struct msdc_host *host, struct mmc_data *data) } }

+static bool msdc_data_prepared(struct mmc_data *data) +{ + return data->host_cookie & MSDC_PREPARE_FLAG; +} + static void msdc_unprepare_data(struct msdc_host *host, struct mmc_data *data) { if (data->host_cookie & MSDC_ASYNC_FLAG) @@ -1484,8 +1489,18 @@ 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); + return; + } + }

/* if SBC is required, we have HW option and SW option. * if HW option is enabled, and SBC does not have "special" flags,