From a7c525191aa725f4ebb7b489cdd7dd854a4e42fb Mon Sep 17 00:00:00 2001
From: Uwe Ohse <uwe@ohse.de>
Date: Sun, 1 Mar 2020 22:35:28 +0000
Subject: [PATCH] may-be-security-fix: avoid possible underflow
Fixes: CVE-2018-10195
[a.heider: mention CVE in commit message]
---
src/zm.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/src/zm.c
+++ b/src/zm.c
@@ -432,10 +432,11 @@ zsdata(const char *buf, size_t length, i
VPRINTF(3,("zsdata: %lu %s", (unsigned long) length,
Zendnames[(frameend-ZCRCE)&3]));
crc = 0;
- do {
+ while (length>0) {
zsendline(*buf); crc = updcrc((0377 & *buf), crc);
buf++;
- } while (--length>0);
+ length--;
+ }
xsendline(ZDLE); xsendline(frameend);
crc = updcrc(frameend, crc);