cypto: mediatek - fix leaks in mtk_desc_ring_alloc

[ Upstream commit 228d284aac61283cde508a925d666f854b57af63 ]

In the init loop, if an error occurs in function 'dma_alloc_coherent',
then goto the err_cleanup section, after run i--,
in the array ring, the struct mtk_ring with index i will not be released,
causing memory leaks

Fixes: 785e5c616c849 ("crypto: mediatek - Add crypto driver support for some MediaTek chips")
Cc: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Xiaoliang Pang <dawning.pang@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
diff --git a/drivers/crypto/mediatek/mtk-platform.c b/drivers/crypto/mediatek/mtk-platform.c
index 03b1436..e4d7ef3 100644
--- a/drivers/crypto/mediatek/mtk-platform.c
+++ b/drivers/crypto/mediatek/mtk-platform.c
@@ -473,13 +473,13 @@
 	return 0;
 
 err_cleanup:
-	for (; i--; ) {
+	do {
 		dma_free_coherent(cryp->dev, MTK_DESC_RING_SZ,
 				  ring[i]->res_base, ring[i]->res_dma);
 		dma_free_coherent(cryp->dev, MTK_DESC_RING_SZ,
 				  ring[i]->cmd_base, ring[i]->cmd_dma);
 		kfree(ring[i]);
-	}
+	} while (i--);
 	return -ENOMEM;
 }