From: Martin Ling <redacted>
Date: Fri, 24 Jan 2020 04:44:47 +0000 (+0000)
Subject: windows: Avoid leak of write buffer on realloc failure.
X-Git-Url: https://sigrok.org/gitweb/?a=commitdiff_plain;h=988ace6c9f8035e5835847d38a6dbf654ea216da;p=libserialport.git

windows: Avoid leak of write buffer on realloc failure.

VS2019 IntelliSense reported:

Warning	C6308: 'realloc' might return null pointer: assigning null
               pointer to 'port->write_buf', which is passed as an
	       argument to 'realloc', will cause the original memory
	       block to be leaked.

This is correct, we would leak the buffer on a realloc failure.

Put the realloc result in a separate variable and handle the error
path before assigning the result to port->write_buf.
---

diff --git a/serialport.c b/serialport.c
index eee453a..422b767 100644
--- a/serialport.c
+++ b/serialport.c
@@ -1838,6 +1838,7 @@ static enum sp_return set_config(struct sp_port *port, struct port_data *data,
 	DEBUG_FMT("Setting configuration for port %s", port->name);
 
 #ifdef _WIN32
+	BYTE* new_buf;
 
 	TRY(await_write_completion(port));
 
@@ -1854,11 +1855,10 @@ static enum sp_return set_config(struct sp_port *port, struct port_data *data,
 
 		/* Allocate write buffer for 50ms of data at baud rate. */
 		port->write_buf_size = max(config->baudrate / (8 * 20), 1);
-		port->write_buf = realloc(port->write_buf,
-					  port->write_buf_size);
-
-		if (!port->write_buf)
+		new_buf = realloc(port->write_buf, port->write_buf_size);
+		if (!new_buf)
 			RETURN_ERROR(SP_ERR_MEM, "Allocating write buffer failed");
+		port->write_buf = new_buf;
 	}
 
 	if (config->bits >= 0)