Make xundump catch extraneous fields

Make deffld() reject fields whose selector has flag NSC_EXTRA set.
Since xundump() doesn't provides space for these, the bug could lead
to buffer overruns.

diff --git a/src/lib/common/xundump.c b/src/lib/common/xundump.c
index 731cac7db58bacbae38070ec91f252d2f38c51ee..d1d6f7e8178fd756a3afe39fa64acbfceb26dfb3 100644 (file)
--- a/src/lib/common/xundump.c
+++ b/src/lib/common/xundump.c
@@ -352,6 +352,8 @@ deffld(int fldno, char *name, int idx)
     if (res < 0)
        return gripe("Header %s of field %d is %s", name, fldno + 1,
                     res == M_NOTUNIQUE ? "ambiguous" : "unknown");
+    if (ca[res].ca_flags == NSC_EXTRA)
+       return gripe("Extraneous header %s in field %d", name, fldno + 1);
     if (ca[res].ca_type != NSC_STRINGY && ca[res].ca_len != 0) {
        if (idx < 0)
            return gripe("Header %s requires an index in field %d",