Index: Makefile.in
==================================================================
--- Makefile.in
+++ Makefile.in
@@ -40,11 +40,11 @@
 
 test: test.c libcackey_g.@SHOBJEXT@
 	$(CC) $(CPPFLAGS) $(CFLAGS) $(LDFLAGS) -o test test.c -Wl,-R,. libcackey_g.@SHOBJEXT@
 
 splint-cackey.txt: cackey.c asn1-x509.c asn1-x509.h config.h
-	splint $(CPPFLAGS) -weak +posixlib -I/usr/include/PCSC -Ipkcs11 cackey.c > splint-cackey.txt
+	splint $(DEBUGCPPFLAGS) -DCACKEY_PARANOID=1 -weak +posixlib -I/usr/include/PCSC -Ipkcs11 cackey.c > splint-cackey.txt
 
 install: libcackey.@SHOBJEXT@
 	-mkdir "$(DESTDIR)$(libdir)"
 	cp "libcackey.@SHOBJEXT@" "$(DESTDIR)$(libdir)/"
 	-cp "libcackey_g.@SHOBJEXT@" "$(DESTDIR)$(libdir)/"

Index: cackey.c
==================================================================
--- cackey.c
+++ cackey.c
@@ -24,10 +24,13 @@
 #  include <string.h>
 #endif
 #ifdef HAVE_PTHREAD_H
 #  include <pthread.h>
 #endif
+#ifdef HAVE_LIMITS_H
+#  include <limits.h>
+#endif
 #ifdef HAVE_ZLIB_H
 #  ifdef HAVE_LIBZ
 #    include <zlib.h>
 #  endif
 #else
@@ -695,10 +698,11 @@
 		scard_est_context_ret = SCardEstablishContext(SCARD_SCOPE_SYSTEM, NULL, NULL, cackey_pcsc_handle);
 		if (scard_est_context_ret != SCARD_S_SUCCESS) {
 			CACKEY_DEBUG_PRINTF("Call to SCardEstablishContext failed (returned %s/%li), returning in failure", CACKEY_DEBUG_FUNC_SCARDERR_TO_STR(scard_est_context_ret), (long) scard_est_context_ret);
 
 			free(cackey_pcsc_handle);
+			cackey_pcsc_handle = NULL;
 
 			cackey_slots_disconnect_all();
 
 			return(CACKEY_PCSC_E_GENERIC);
 		}
@@ -714,10 +718,11 @@
 		scard_est_context_ret = SCardEstablishContext(SCARD_SCOPE_SYSTEM, NULL, NULL, cackey_pcsc_handle);
 		if (scard_est_context_ret != SCARD_S_SUCCESS) {
 			CACKEY_DEBUG_PRINTF("Call to SCardEstablishContext failed (returned %s/%li), returning in failure", CACKEY_DEBUG_FUNC_SCARDERR_TO_STR(scard_est_context_ret), (long) scard_est_context_ret);
 
 			free(cackey_pcsc_handle);
+			cackey_pcsc_handle = NULL;
 
 			cackey_slots_disconnect_all();
 
 			return(CACKEY_PCSC_E_GENERIC);
 		}
@@ -756,12 +761,15 @@
 		return(CACKEY_PCSC_S_OK);
 	}
 
 	scard_rel_context_ret = SCardReleaseContext(*cackey_pcsc_handle);
 
-	free(cackey_pcsc_handle);
-	cackey_pcsc_handle = NULL;
+	if (cackey_pcsc_handle) {
+		free(cackey_pcsc_handle);
+	
+		cackey_pcsc_handle = NULL;
+	}
 
 	if (scard_rel_context_ret != SCARD_S_SUCCESS) {
 		return(CACKEY_PCSC_E_GENERIC);
 	}
 
@@ -1271,15 +1279,25 @@
 		}
 
 		offset += count;
 
 		if (count < max_count) {
-			CACKEY_DEBUG_PRINTF("Short read -- count = %i, cmd[1] = %i", count, cmd[1]);
+			CACKEY_DEBUG_PRINTF("Short read -- count = %i, cmd[1] = %i", (int) count, (int) cmd[1]);
 
 			break;
 		}
 	}
+
+#ifdef CACKEY_PARANOID
+#  ifdef _POSIX_SSIZE_MAX
+	if (offset > _POSIX_SSIZE_MAX) {
+		CACKEY_DEBUG_PRINTF("Offset exceeds maximum value, returning in failure. (max = %li, offset = %lu)", (long) _POSIX_SSIZE_MAX, (unsigned long) offset);
+
+		return(-1);
+	}
+#  endif
+#endif
 
 	CACKEY_DEBUG_PRINTF("Returning in success, read %lu bytes", (unsigned long) offset);
 
 	return(offset);
 }
@@ -1870,10 +1888,20 @@
 		return(-1);
 	}
 
 	/* End transaction */
 	cackey_end_transaction(slot);
+
+#ifdef CACKEY_PARANOID
+#  ifdef _POSIX_SSIZE_MAX
+	if (outbuflen > _POSIX_SSIZE_MAX) {
+		CACKEY_DEBUG_PRINTF("Outbuflen exceeds maximum value, returning in failure. (max = %li, outbuflen = %lu)", (long) _POSIX_SSIZE_MAX, (unsigned long) outbuflen);
+
+		return(-1);
+	}
+#  endif
+#endif
 
 	CACKEY_DEBUG_PRINTF("Returning in success.");
 
 	return(outbuflen);
 }
@@ -2004,10 +2032,20 @@
 
 		if (x509_read_ret <= 0) {
 			return(-1);
 		}
 	}
+
+#ifdef CACKEY_PARANOID
+#  ifdef _POSIX_SSIZE_MAX
+	if (x509_read_ret > _POSIX_SSIZE_MAX) {
+		CACKEY_DEBUG_PRINTF("x509_read_ret exceeds maximum value, returning in failure. (max = %li, x509_read_ret = %lu)", (long) _POSIX_SSIZE_MAX, (unsigned long) x509_read_ret);
+
+		return(-1);
+	}
+#  endif
+#endif
 
 	return(x509_read_ret);
 }
 
 /* Returns 0 on success */