1 files changed, 9 insertions, 0 deletions
diff --git a/lib/util/asn1.c b/lib/util/asn1.c
index b716da63c0..c23bf65b8d 100644
--- a/lib/util/asn1.c
+++ b/lib/util/asn1.c
@@ -885,10 +885,19 @@ bool asn1_read_ContextSimple(struct asn1_data *data, uint8_t num, DATA_BLOB *blo
 bool asn1_read_implicit_Integer(struct asn1_data *data, int *i)
 {
 	uint8_t b;
+	bool first_byte = true;
 	*i = 0;
 
 	while (!data->has_error && asn1_tag_remaining(data)>0) {
 		if (!asn1_read_uint8(data, &b)) return false;
+		if (first_byte) {
+			if (b & 0x80) {
+				/* Number is negative.
+				   Set i to -1 for sign extend. */
+				*i = -1;
+			}
+			first_byte = false;
+		}
 		*i = (*i << 8) + b;
 	}
 	return !data->has_error;