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spi: Ensure that sg_table won't be used after being freed

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[ 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>
This commit is contained in:
Marek Szyprowski
2022-09-30 13:34:08 +02:00
committed by Greg Kroah-Hartman
parent 96a3ddb870
commit d9e25dc053
1 changed files with 2 additions and 0 deletions
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drivers/spi/spi.c
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@@ -946,6 +946,8 @@ void spi_unmap_buf(struct spi_controller *ctlr, struct device *dev,
if (sgt->orig_nents) { if (sgt->orig_nents) {
dma_unmap_sg(dev, sgt->sgl, sgt->orig_nents, dir); dma_unmap_sg(dev, sgt->sgl, sgt->orig_nents, dir);
sg_free_table(sgt); sg_free_table(sgt);
sgt->orig_nents = 0;
sgt->nents = 0;
} }
} }