From: Takashi Iwai <tiwai@suse.de>
Subject: [PATCH v2] mmc: sdhci: Clear unused bounce buffer at DMA mmap error
 path
Date: Fri, 11 Jun 2021 12:19:48 +0200
Message-Id: <20210611101948.18972-1-tiwai@suse.de>
Patch-mainline: Submitted, linux-mmc ML
References: bsc#1187039

When DMA-mapping of the bounce buffer fails, the driver tries to fall
back, but it leaves the allocated host->bounce_buffer although its
size is zero.  Later on, the driver checks the use of bounce buffer
with host->bounce_buffer pointer, and it tries to use the buffer
incorrectly, resulting in Oops.

This patch clears the release the unused buffer and clears the
bounce_buffer pointer for addressing the problem.

Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

---
v1->v2: correct the device pointer to mmc_dev(mmc)

 drivers/mmc/host/sdhci.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -3929,9 +3929,13 @@ static void sdhci_allocate_bounce_buffer
 					   bounce_size,
 					   DMA_BIDIRECTIONAL);
 	ret = dma_mapping_error(mmc->parent, host->bounce_addr);
-	if (ret)
+	if (ret) {
+		devm_kfree(mmc->parent, host->bounce_buffer);
+		host->bounce_buffer = NULL;
 		/* Again fall back to max_segs == 1 */
 		return;
+	}
+
 	host->bounce_buffer_size = bounce_size;
 
 	/* Lie about this since we're bouncing */