See https://trac.xiph.org/ticket/1209 for the bug report.  This patch comes
from: https://trac.xiph.org/changeset/13263?format=diff&new=13263

Index: /trunk/vorbis-tools/oggdec/oggdec.c
===================================================================
--- vorbis-tools/oggdec/oggdec.c (revision 12221)
+++ vorbis-tools/oggdec/oggdec.c (revision 13263)
@@ -256,4 +256,5 @@
     int bs = 0;
     char buf[8192], outbuf[8192];
+    char *p_outbuf;
     int buflen = 8192;
     unsigned int written = 0;
@@ -325,7 +326,11 @@
           /* Then permute! */
           permute_channels(buf, outbuf, ret, channels, bits/8);
-        }
-
-        if(fwrite(outbuf, 1, ret, out) != ret) {
+          p_outbuf = outbuf;
+        }
+        else {
+          p_outbuf = buf;
+        }
+
+        if(fwrite(p_outbuf, 1, ret, out) != ret) {
             fprintf(stderr, "Error writing to file: %s\n", strerror(errno));
             ov_clear(&vf);