Replace recallocarray() with a realloc() + memset() combo.

recallocarray(), with its guarantee that memory becoming unallocated is
explicitly discarded, is too slow. In rpki-client forming one particular
ibuf takes more then 4mins because every recallocarray() call ends up
doing a fresh malloc + memcpy + freezero call.
For sensitive data use ibuf_open() instead of ibuf_dynamic() to avoid
any memory reallocations.
OK tb@

diff --git a/lib/libutil/imsg-buffer.c b/lib/libutil/imsg-buffer.c
index 0708f48..d45802d 100644 (file)
--- a/lib/libutil/imsg-buffer.c
+++ b/lib/libutil/imsg-buffer.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: imsg-buffer.c,v 1.18 2023/12/12 15:47:41 claudio Exp $        */
+/*     $OpenBSD: imsg-buffer.c,v 1.19 2024/08/26 13:57:34 claudio Exp $        */
 
 /*
  * Copyright (c) 2023 Claudio Jeker <claudio@openbsd.org>
@@ -94,9 +94,10 @@ ibuf_realloc(struct ibuf *buf, size_t len)
                return (-1);
        }
 
-       b = recallocarray(buf->buf, buf->size, buf->wpos + len, 1);
+       b = realloc(buf->buf, buf->wpos + len);
        if (b == NULL)
                return (-1);
+       memset(b + buf->size, 0, buf->wpos + len - buf->size);
        buf->buf = b;
        buf->size = buf->wpos + len;