[PATCH 4.14 072/193] crypto: sun4i-ss - Fix invalid calculation of hash end

[Greg Kroah-Hartman]

[ Upstream commit f87391558acf816b48f325a493d81d45dec40da0 ]

When nbytes < 4, end is wronlgy set to a negative value which, due to
uint, is then interpreted to a large value leading to a deadlock in the
following code.

This patch fix this problem.

Fixes: 6298e948215f ("crypto: sunxi-ss - Add Allwinner Security System crypto 
accelerator")
Signed-off-by: Corentin Labbe <clabbe.montj...@gmail.com>
Signed-off-by: Herbert Xu <herb...@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 drivers/crypto/sunxi-ss/sun4i-ss-hash.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/crypto/sunxi-ss/sun4i-ss-hash.c 
b/drivers/crypto/sunxi-ss/sun4i-ss-hash.c
index a4b5ff2b72f87..f6936bb3b7be4 100644
--- a/drivers/crypto/sunxi-ss/sun4i-ss-hash.c
+++ b/drivers/crypto/sunxi-ss/sun4i-ss-hash.c
@@ -240,7 +240,10 @@ static int sun4i_hash(struct ahash_request *areq)
                }
        } else {
                /* Since we have the flag final, we can go up to modulo 4 */
-               end = ((areq->nbytes + op->len) / 4) * 4 - op->len;
+               if (areq->nbytes < 4)
+                       end = 0;
+               else
+                       end = ((areq->nbytes + op->len) / 4) * 4 - op->len;
        }
 
        /* TODO if SGlen % 4 and !op->len then DMA */
-- 
2.20.1