linux-kernel - [PATCH 5.13 085/127] iommu/dma: Fix leak in non-contiguous API

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Date:   Tue, 24 Aug 2021 12:55:25 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Ezequiel Garcia <ezequiel@...labora.com>,
        Christoph Hellwig <hch@....de>, Joerg Roedel <jroedel@...e.de>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.13 085/127] iommu/dma: Fix leak in non-contiguous API

From: Ezequiel Garcia <ezequiel@...labora.com>

[ Upstream commit 0fbea680540108b09db7b26d9f4d24236d58a6ad ]

Currently, iommu_dma_alloc_noncontiguous() allocates a
struct dma_sgt_handle object to hold some state needed for
iommu_dma_free_noncontiguous().

However, the handle is neither freed nor returned explicitly by
the ->alloc_noncontiguous method, and therefore seems leaked.
This was found by code inspection, so please review carefully and test.

As a side note, it appears the struct dma_sgt_handle type is exposed
to users of the DMA-API by linux/dma-map-ops.h, but is has no users
or functions returning the type explicitly.

This may indicate it's a good idea to move the struct dma_sgt_handle type
to drivers/iommu/dma-iommu.c. The decision is left to maintainers :-)

Cc: stable@...r.kernel.org
Fixes: e817ee5f2f95c ("dma-iommu: implement ->alloc_noncontiguous")
Signed-off-by: Ezequiel Garcia <ezequiel@...labora.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Link: https://lore.kernel.org/r/20210723010552.50969-1-ezequiel@collabora.com
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/iommu/dma-iommu.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 5d96fcc45fec..698707699327 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -768,6 +768,7 @@ static void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
 	__iommu_dma_unmap(dev, sgt->sgl->dma_address, size);
 	__iommu_dma_free_pages(sh->pages, PAGE_ALIGN(size) >> PAGE_SHIFT);
 	sg_free_table(&sh->sgt);
+	kfree(sh);
 }
 #endif /* CONFIG_DMA_REMAP */

-- 
2.30.2