FAILED: patch "[PATCH] staging: ccree: check DMA pool buf !NULL before free" failed to apply to 4.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 2f7caf6b02145bd9cd9d0b56204f51a5fefe7790 Mon Sep 17 00:00:00 2001
From: Gilad Ben-Yossef <gilad@benyossef.com>
Date: Sun, 7 Jan 2018 12:14:24 +0000
Subject: [PATCH] staging: ccree: check DMA pool buf !NULL before free

If we ran out of DMA pool buffers, we get into the unmap
code path with a NULL before. Deal with this by checking
the virtual mapping is not NULL.

Cc: stable@vger.kernel.org
Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/ccree/ssi_buffer_mgr.c b/drivers/staging/ccree/ssi_buffer_mgr.c
index e85bb53a3289..78288ed75281 100644
--- a/drivers/staging/ccree/ssi_buffer_mgr.c
+++ b/drivers/staging/ccree/ssi_buffer_mgr.c
@@ -465,7 +465,8 @@ void cc_unmap_blkcipher_request(struct device *dev, void *ctx,
 				 DMA_TO_DEVICE);
 	}
 	/* Release pool */
-	if (req_ctx->dma_buf_type == CC_DMA_BUF_MLLI) {
+	if (req_ctx->dma_buf_type == CC_DMA_BUF_MLLI &&
+	    req_ctx->mlli_params.mlli_virt_addr) {
 		dma_pool_free(req_ctx->mlli_params.curr_pool,
 			      req_ctx->mlli_params.mlli_virt_addr,
 			      req_ctx->mlli_params.mlli_dma_addr);