From: Mark Wooding <mdw@distorted.org.uk>
Date: Fri, 18 Oct 2019 21:45:01 +0000 (+0100)
Subject: math/ec-exp.h: Fix segfault when base point is at infinity.
X-Git-Tag: 2.4.5~18
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/catacomb/commitdiff_plain/b67c17c38e660bbf6f68e23f27af5a974a3b08ac?ds=inline

math/ec-exp.h: Fix segfault when base point is at infinity.
---

diff --git a/math/ec-exp.h b/math/ec-exp.h
index 6cad7537..b393d7ec 100644
--- a/math/ec-exp.h
+++ b/math/ec-exp.h
@@ -37,9 +37,13 @@
 #define EXP_TYPE ec
 
 #define EXP_COPY(d, p) do {						\
-  (d).x = MP_COPY((p).x);						\
-  (d).y = MP_COPY((p).y);						\
-  (d).z = (p).z ? MP_COPY((p).z) : MP_NEW;				\
+  if (EC_ATINF(&(p)))							\
+    (d).x = (d).y = (d).z = MP_NEW;					\
+  else {								\
+    (d).x = MP_COPY((p).x);						\
+    (d).y = MP_COPY((p).y);						\
+    (d).z = (p).z ? MP_COPY((p).z) : MP_NEW;				\
+  }									\
 } while (0)
 #define EXP_DROP(x) EC_DESTROY(&(x))