linux-kernel - [PATCH 1/2] crypto: s5p-sss - Fix use after free of copied input buffer in error path

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Date:	Tue, 19 Apr 2016 15:44:11 +0200
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Vladimir Zapolskiy <vz@...ia.com>, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org
Cc:	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: [PATCH 1/2] crypto: s5p-sss - Fix use after free of copied input
 buffer in error path

The driver makes copies of memory (input or output scatterlists) if they
are not aligned. In s5p_aes_crypt_start() error path (on unsuccessful
initialization of output scatterlist), if input scatterlist was not
aligned, the driver first freed copied input memory and then unmapped it
from the device, instead of doing otherwise (unmap and then free).

This was wrong in two ways:
1. Freed pages were still mapped to the device.
2. The dma_unmap_sg() iterated over freed scatterlist structure.

The call to s5p_free_sg_cpy() in this error path is not needed because
the copied scatterlists will be freed by s5p_aes_complete().

Fixes: 9e4a1100a445 ("crypto: s5p-sss - Handle unaligned buffers")
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
---
 drivers/crypto/s5p-sss.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/crypto/s5p-sss.c b/drivers/crypto/s5p-sss.c
index 4f6d5b3ec418..b0484d4d68d9 100644
--- a/drivers/crypto/s5p-sss.c
+++ b/drivers/crypto/s5p-sss.c
@@ -577,7 +577,6 @@ static void s5p_aes_crypt_start(struct s5p_aes_dev *dev, unsigned long mode)
 	return;

 outdata_error:
-	s5p_free_sg_cpy(dev, &dev->sg_src_cpy);
 	s5p_unset_indata(dev);

 indata_error:
-- 
1.9.1