releases/5.15.75/spi-ensure-that-sg_table-won-t-be-used-after-being-f.patch

From fc4a4d15f0bafeda1b706497f948dfa92db27cca Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Fri, 30 Sep 2022 13:34:08 +0200
Subject: spi: Ensure that sg_table won't be used after being freed

From: Marek Szyprowski <m.szyprowski@samsung.com>

[ Upstream commit 8e9204cddcc3fea9affcfa411715ba4f66e97587 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/spi/spi.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 556d65af5e23..06dd1be54925 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1007,6 +1007,8 @@ void spi_unmap_buf(struct spi_controller *ctlr, struct device *dev,
 	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;
 	}
 }
 
-- 
2.35.1