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From:   Tero Kristo <t-kristo@ti.com>
To:     <herbert@gondor.apana.org.au>, <davem@davemloft.net>,
        <linux-crypto@vger.kernel.org>
CC:     <linux-omap@vger.kernel.org>
Subject: [PATCHv3 3/7] crypto: omap-crypto: fix userspace copied buffer access
Date:   Tue, 26 May 2020 17:21:04 +0300
Message-ID: <20200526142104.7362-1-t-kristo@ti.com>
In-Reply-To: <20200522131247.GA27255@gondor.apana.org.au>
References: <20200522131247.GA27255@gondor.apana.org.au>
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Sender: linux-crypto-owner@vger.kernel.org
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In case buffers are copied from userspace, directly accessing the page
will most likely fail because it hasn't been mapped into the kernel
memory space. Fix the issue by forcing a kmap / kunmap within the
cleanup functionality.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
---
v3:
  - Added PageSlab() check to the cache flushing portion, and changed
    the used flush API to be flush_kernel_dcache_page()

 drivers/crypto/omap-crypto.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/crypto/omap-crypto.c b/drivers/crypto/omap-crypto.c
index cc88b7362bc2..94b2dba90f0d 100644
--- a/drivers/crypto/omap-crypto.c
+++ b/drivers/crypto/omap-crypto.c
@@ -178,11 +178,17 @@ static void omap_crypto_copy_data(struct scatterlist *src,
 		amt = min(src->length - srco, dst->length - dsto);
 		amt = min(len, amt);
 
-		srcb = sg_virt(src) + srco;
-		dstb = sg_virt(dst) + dsto;
+		srcb = kmap_atomic(sg_page(src)) + srco + src->offset;
+		dstb = kmap_atomic(sg_page(dst)) + dsto + dst->offset;
 
 		memcpy(dstb, srcb, amt);
 
+		if (!PageSlab(sg_page(dst)))
+			flush_kernel_dcache_page(sg_page(dst));
+
+		kunmap_atomic(srcb);
+		kunmap_atomic(dstb);
+
 		srco += amt;
 		dsto += amt;
 		len -= amt;
-- 
2.17.1

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