From: Stephan Bosch <stephan.bosch@open-xchange.com>
Date: Tue, 29 Jun 2021 20:45:33 +0000 (+0200)
Subject: lib-program-client: program-client-remote - Fix signed integer arithmetic.
X-Git-Tag: 2.3.17~256
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=bb6efaa41774af1981df1be26d6e5e11108c1b14;p=thirdparty%2Fdovecot%2Fcore.git

lib-program-client: program-client-remote - Fix signed integer arithmetic.

Make type cast explicit to gain ubsan approval. Also prevent negative
reserve_mod from having unexpected effect.
---

diff --git a/src/lib-program-client/program-client-remote.c b/src/lib-program-client/program-client-remote.c
index c29b19ebd1..858abe6569 100644
--- a/src/lib-program-client/program-client-remote.c
+++ b/src/lib-program-client/program-client-remote.c
@@ -159,7 +159,7 @@ static ssize_t program_client_istream_read(struct istream_private *stream)
 
 				reserved = (stream->buffer[pos - 1] == '\n' &&
 					    pos > 1 ? 2 : 1);
-				reserve_mod = reserved - old_reserved;
+				reserve_mod = (ssize_t)reserved - (ssize_t)old_reserved;
 				pos -= reserved;
 			}
 			if (ret == 0) {
@@ -168,7 +168,7 @@ static ssize_t program_client_istream_read(struct istream_private *stream)
 				   not visible to application. */
 				break;
 			}
-			if (ret >= reserve_mod) {
+			if (ret > 0 && ret >= reserve_mod) {
 				/* Subtract additional reserved bytes */
 				ret -= reserve_mod;
 			}