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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Gilad Ben-Yossef <gilad@benyossef.com>,
        Corentin Labbe <clabbe.montjoie@gmail.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.17 0230/1126] crypto: ccree - dont attempt 0 len DMA mappings
Date:   Tue,  5 Apr 2022 09:16:17 +0200
Message-Id: <20220405070414.359472455@linuxfoundation.org>
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From: Gilad Ben-Yossef <gilad@benyossef.com>

[ Upstream commit 1fb37b5692c915edcc2448a6b37255738c7c77e0 ]

Refuse to try mapping zero bytes as this may cause a fault
on some configurations / platforms and it seems the prev.
attempt is not enough and we need to be more explicit.

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Reported-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Fixes: ce0fc6db38de ("crypto: ccree - protect against empty or NULL
scatterlists")
Tested-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/crypto/ccree/cc_buffer_mgr.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/crypto/ccree/cc_buffer_mgr.c b/drivers/crypto/ccree/cc_buffer_mgr.c
index a5e041d9d2cf..11e0278c8631 100644
--- a/drivers/crypto/ccree/cc_buffer_mgr.c
+++ b/drivers/crypto/ccree/cc_buffer_mgr.c
@@ -258,6 +258,13 @@ static int cc_map_sg(struct device *dev, struct scatterlist *sg,
 {
 	int ret = 0;
 
+	if (!nbytes) {
+		*mapped_nents = 0;
+		*lbytes = 0;
+		*nents = 0;
+		return 0;
+	}
+
 	*nents = cc_get_sgl_nents(dev, sg, nbytes, lbytes);
 	if (*nents > max_sg_nents) {
 		*nents = 0;
-- 
2.34.1