[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 <k...@umn.edu>
---
 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