diff mbox series

[5.10,135/390] spi: Ensure that sg_table wont be used after being freed

Message ID 20221024113028.425937864@linuxfoundation.org
State New
Headers
Series None |

Commit Message

Greg KH Oct. 24, 2022, 11:28 a.m. UTC 
  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(+)
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Patch

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 6ea7b286c80c..857a1399850c 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -946,6 +946,8 @@  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;
 	}
 }