[PATCH 4.4 079/193] ALSA: hda/ca0132 - fix possible NULL pointer use

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Arnd Bergmann <arnd@xxxxxxxx>

commit 46a049dae771b95e77ac6c823330f4a60f600236 upstream.

gcc-7 caught what it considers a NULL pointer dereference:

sound/pci/hda/patch_ca0132.c: In function 'dspio_scp.constprop':
sound/pci/hda/patch_ca0132.c:1487:4: error: argument 1 null where non-null expected [-Werror=nonnull]

This is plausible from looking at the function, as we compare 'reply'
to NULL earlier in it. I have not tried to analyze if there are constraints
that make it impossible to hit the bug, but adding another NULL check in
the end kills the warning and makes the function more robust.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 sound/pci/hda/patch_ca0132.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/sound/pci/hda/patch_ca0132.c
+++ b/sound/pci/hda/patch_ca0132.c
@@ -1482,6 +1482,9 @@ static int dspio_scp(struct hda_codec *c
 		} else if (ret_size != reply_data_size) {
 			codec_dbg(codec, "RetLen and HdrLen .NE.\n");
 			return -EINVAL;
+		} else if (!reply) {
+			codec_dbg(codec, "NULL reply\n");
+			return -EINVAL;
 		} else {
 			*reply_len = ret_size*sizeof(unsigned int);
 			memcpy(reply, scp_reply.data, *reply_len);