1 files changed, 2 insertions, 1 deletions
diff --git a/scan_asn1tagint.c b/scan_asn1tagint.c
index 49a9974..2c23fa2 100644
--- a/scan_asn1tagint.c
+++ b/scan_asn1tagint.c
@@ -3,9 +3,10 @@
 size_t scan_asn1tagint(const char* src,const char* max,unsigned long* val) {
   const char* orig=src;
   unsigned long l=0;
+  if (src==max || (unsigned char)src[0]==0x80) return 0;	/* catch non-minimal encoding */
   for (;; ++src) {
     if (src>=max) return 0;
-    if (l>(((unsigned long)-1)>>7)) return 0;	/* catch integer overflow */
+    if (l>>(sizeof(l)*8-7)) return 0;	/* catch integer overflow */
     l=l*128+(*src&0x7F);
     if (!(*src&0x80)) break;
   }