From 8e9204cddcc3fea9affcfa411715ba4f66e97587 Mon Sep 17 00:00:00 2001
From: Marek Szyprowski <m.szyprowski@samsung.com>
Date: Fri, 30 Sep 2022 13:34:08 +0200
Subject: [PATCH] spi: Ensure that sg_table won't be used after being freed
Git-commit: 8e9204cddcc3fea9affcfa411715ba4f66e97587
Patch-mainline: v6.1-rc1
References: git-fixes

SPI code checks for non-zero sgt->orig_nents to determine if the buffer
has been DMA-mapped. Ensure that sg_table is really zeroed after free to
avoid potential NULL pointer dereference if the given SPI xfer object is
reused again without being DMA-mapped.

Fixes: 0c17ba73c08f ("spi: Fix cache corruption due to DMA/PIO overlap")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20220930113408.19720-1-m.szyprowski@samsung.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/spi/spi.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1007,6 +1007,8 @@ void spi_unmap_buf(struct spi_controller
 	if (sgt->orig_nents) {
 		dma_unmap_sg(dev, sgt->sgl, sgt->orig_nents, dir);
 		sg_free_table(sgt);
+		sgt->orig_nents = 0;
+		sgt->nents = 0;
 	}
 }