linux-kernel - [PATCH] mmc: host: fix a possible null pointer access.

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Date:   Tue, 17 Dec 2019 11:17:52 +0800
From:   Pan Zhang <zhangpan26@...wei.com>
To:     <zhangpan26@...wei.com>, <hushiyuan@...wei.com>,
        <jh80.chung@...sung.com>, <ulf.hansson@...aro.org>,
        <p.zabel@...gutronix.de>
CC:     <linux-mmc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] mmc: host: fix a possible null pointer access.

3419     if (host->slot &&
3420         (mmc_can_gpio_cd(host->slot->mmc) ||
3421          !mmc_card_is_removable(host->slot->mmc))) {
3422         ret = clk_prepare_enable(host->biu_clk);
3423         if (ret)
3424             return ret;
3425     }

We previously assumed 'host->slot' could be null (see line 3419).

The following situation is similar, so add a judgement.

Signed-off-by: Pan Zhang <zhangpan26@...wei.com>
---
 drivers/mmc/host/dw_mmc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index fc9d4d0..8e27c52 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -3454,7 +3454,7 @@ int dw_mci_runtime_resume(struct device *dev)
 	mci_writel(host, CTRL, SDMMC_CTRL_INT_ENABLE);
 
 
-	if (host->slot->mmc->pm_flags & MMC_PM_KEEP_POWER)
+	if (host->slot && (host->slot->mmc->pm_flags & MMC_PM_KEEP_POWER))
 		dw_mci_set_ios(host->slot->mmc, &host->slot->mmc->ios);
 
 	/* Force setup bus to guarantee available clock output */
-- 
2.7.4