From 2550bbfd495227945e17ed1fa1c05bce4753b86b Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Tue, 29 May 2018 16:15:12 +0200
Subject: [PATCH] dma-direct: don't crash on device without dma_mask

Print a useful warning instead.

Reported-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 lib/dma-direct.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/dma-direct.c b/lib/dma-direct.c
index a48f94eff62e..8be8106270c2 100644
--- a/lib/dma-direct.c
+++ b/lib/dma-direct.c
@@ -34,6 +34,13 @@ check_addr(struct device *dev, dma_addr_t dma_addr, size_t size,
 		const char *caller)
 {
 	if (unlikely(dev && !dma_capable(dev, dma_addr, size))) {
+		if (!dev->dma_mask) {
+			dev_err(dev,
+				"%s: call on device without dma_mask\n",
+				caller);
+			return false;
+		}
+
 		if (*dev->dma_mask >= DMA_BIT_MASK(32)) {
 			dev_err(dev,
 				"%s: overflow %pad+%zu of device mask %llx\n",
-- 
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