[PATCH] sound: echoaudio: add a check for ioremap_nocache

[Kangjie Lu]

In case ioremap_nocache fails, the fix releases chip and returns
an error code upstream to avoid NULL pointer dereference.

Signed-off-by: Kangjie Lu <kjlu@xxxxxxx>
---
 sound/pci/echoaudio/echoaudio.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/sound/pci/echoaudio/echoaudio.c b/sound/pci/echoaudio/echoaudio.c
index ea876b0b02b9..dc0084dc8550 100644
--- a/sound/pci/echoaudio/echoaudio.c
+++ b/sound/pci/echoaudio/echoaudio.c
@@ -1952,6 +1952,11 @@ static int snd_echo_create(struct snd_card *card,
 	}
 	chip->dsp_registers = (volatile u32 __iomem *)
 		ioremap_nocache(chip->dsp_registers_phys, sz);
+	if (!chip->dsp_registers) {
+		dev_err(chip->card->dev, "ioremap failed\n");
+		snd_echo_free(chip);
+		return -ENOMEM;
+	}
 
 	if (request_irq(pci->irq, snd_echo_interrupt, IRQF_SHARED,
 			KBUILD_MODNAME, chip)) {
-- 
2.17.1