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[Openvpn-devel,1/2,v2] buffer: use memcpy in buf_catrunc

Message ID 20230329090447.246561-1-frank@lichtenheld.com
State Superseded
Headers show
Series [Openvpn-devel,1/2,v2] buffer: use memcpy in buf_catrunc | expand

Commit Message

Frank Lichtenheld March 29, 2023, 9:04 a.m. UTC 
Since we use strlen() to determine the length
and then check it ourselves, there is really
no point in using strncpy.

But the compiler might complain that we use
the output of strlen() for the length of
strncpy which is usually a sign for bugs:

error: ‘strncpy’ specified bound depends
 on the length of the source argument
 [-Werror=stringop-overflow=]

Warning was at least triggered for
mingw-gcc version 10-win32 20220113.

Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
---
 src/openvpn/buffer.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

v2:
 - make len size_t and change code to avoid any theoretical overflows
 - remove useless casts
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Patch

diff --git a/src/openvpn/buffer.c b/src/openvpn/buffer.c
index d099795b..886eb2c3 100644
--- a/src/openvpn/buffer.c
+++ b/src/openvpn/buffer.c
@@ -316,10 +316,10 @@  buf_catrunc(struct buffer *buf, const char *str)
 {
     if (buf_forward_capacity(buf) <= 1)
     {
-        int len = (int) strlen(str) + 1;
+        size_t len = strlen(str);
         if (len < buf_forward_capacity_total(buf))
         {
-            strncpynt((char *)(buf->data + buf->capacity - len), str, len);
+            memcpy(buf->data + buf->capacity - len - 1, str, len + 1);
         }
     }
 }