audio flinger: add check in getInputBufferSize()

Make sure that the sample rate passed to getInputBufferSize()
is not 0 to avoid divide by 0 in destinationFramesPossible()

Also check the channel mask parameter for validity.

bug: 26866012
Change-Id: Ifabbf56cadb0db104f99230cacdba30e0c6a0a3a
diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index f4bd1c4..6f34271 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -1161,7 +1161,9 @@
     if (ret != NO_ERROR) {
         return 0;
     }
-    if (!audio_is_valid_format(format) || !audio_is_linear_pcm(format)) {
+    if ((sampleRate == 0) ||
+            !audio_is_valid_format(format) || !audio_is_linear_pcm(format) ||
+            !audio_is_input_channel(channelMask)) {
         return 0;
     }