[Openvpn-devel,v4] ssl: Clean up type handling in write_string()

Message ID 20251104091940.10826-1-gert@greenie.muc.de
State New
Headers show
Series [Openvpn-devel,v4] ssl: Clean up type handling in write_string() | expand

Commit Message

Gert Doering Nov. 4, 2025, 9:19 a.m. UTC
From: Frank Lichtenheld <frank@lichtenheld.com>

Make better checks for the maxlen input value.

Change-Id: I3309265edf8d6bea7bd73b21eef589a92ede6e0a
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1300
---

This change was reviewed on Gerrit and approved by at least one
developer. I request to merge it to master.

Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1300
This mail reflects revision 4 of this Change.

Acked-by according to Gerrit (reflected above):
Gert Doering <gert@greenie.muc.de>

Patch

diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c
index d177730..e03b81e 100644
--- a/src/openvpn/ssl.c
+++ b/src/openvpn/ssl.c
@@ -1780,20 +1780,16 @@ 
     return true;
 }
 
-#if defined(__GNUC__) || defined(__clang__)
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wconversion"
-#endif
-
 static bool
 write_string(struct buffer *buf, const char *str, const int maxlen)
 {
-    const int len = strlen(str) + 1;
-    if (len < 1 || (maxlen >= 0 && len > maxlen))
+    const size_t len = strlen(str) + 1;
+    const size_t real_maxlen = (maxlen >= 0 && maxlen <= UINT16_MAX) ? (size_t)maxlen : UINT16_MAX;
+    if (len > real_maxlen)
     {
         return false;
     }
-    if (!buf_write_u16(buf, len))
+    if (!buf_write_u16(buf, (uint16_t)len))
     {
         return false;
     }
@@ -1833,6 +1829,11 @@ 
     return len;
 }
 
+#if defined(__GNUC__) || defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wconversion"
+#endif
+
 static char *
 read_string_alloc(struct buffer *buf)
 {