laforge submitted this change.

View Change

OmapiCallbackHandlerVpcd: add check to filter shortTPDUs

Related: OS#6836
Change-Id: I4e76afd7cf4d63c67b1525202fbe74e0796b2ba3
---
M app/src/main/java/org/osmocom/androidApduProxy/OmapiCallbackHandlerVpcd.java
1 file changed, 10 insertions(+), 0 deletions(-)

diff --git a/app/src/main/java/org/osmocom/androidApduProxy/OmapiCallbackHandlerVpcd.java b/app/src/main/java/org/osmocom/androidApduProxy/OmapiCallbackHandlerVpcd.java
index c71581c..0b880fb 100644
--- a/app/src/main/java/org/osmocom/androidApduProxy/OmapiCallbackHandlerVpcd.java
+++ b/app/src/main/java/org/osmocom/androidApduProxy/OmapiCallbackHandlerVpcd.java
@@ -101,6 +101,16 @@
             @Override
             public byte[] vpcdTransact(byte[] tpdu) {
                 Log.i("PROXY", "Exchanging TPDU...\n");
+
+                //All TPDUs that we receive here should have a minimum length of 5 bytes. Under normal conditins, short
+                //TPDUs should not occurr as they should already be filtered out by the layers that call this method.
+                //To ensure seamless operation, let's check the TPDU length and reject short TPDUs immediately.
+                if (tpdu.length < 5) {
+                    Log.e("PROXY", String.format("Rejecting short TPDU (%s)...\n", Utils.b2h(tpdu)));
+                    //see also ISO/IEC 7816-4, table 5 (wrong length; no further indication)
+                    return (Utils.h2b("6700"));
+                }
+
                 //In case the TPDU contains a SELECT by DF-Name, which is forbidden by OMAPI by design, we must
                 //find an alternative solution: In case the SELECT targets the currently selected application,
                 //we just use the FID 7FFF, which is an alias for the currently selected application. In case the

To view, visit change 41801. To unsubscribe, or for help writing mail filters, visit settings.