introduce xcalloc() and xasprintf() failure-checked allocations functions

and use them throughout openssh

xcalloc is particularly important because malloc(nmemb * size) is a
dangerous idiom (subject to integer overflow) and it is time for it to
die

feedback and ok deraadt@

1 files changed, 5 insertions, 12 deletions

diff --git a/usr.bin/ssh/sshconnect.c b/usr.bin/ssh/sshconnect.c
index 8ec5e8df8b4..19b074627c7 100644
--- a/usr.bin/ssh/sshconnect.c
+++ b/usr.bin/ssh/sshconnect.c
@@ -62,7 +62,6 @@ ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
 	int pin[2], pout[2];
 	pid_t pid;
 	char strport[NI_MAXSERV];
-	size_t len;
 
 	/* Convert the port number into a string. */
 	snprintf(strport, sizeof strport, "%hu", port);
@@ -74,10 +73,7 @@ ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
 	 * Use "exec" to avoid "sh -c" processes on some platforms
 	 * (e.g. Solaris)
 	 */
-	len = strlen(proxy_command) + 6;
-	tmp = xmalloc(len);
-	strlcpy(tmp, "exec ", len);
-	strlcat(tmp, proxy_command, len);
+	xasprintf(&tmp, "exec %s", proxy_command);
 	command_string = percent_expand(tmp, "h", host,
 	    "p", strport, (char *)NULL);
 	xfree(tmp);
@@ -205,7 +201,7 @@ timeout_connect(int sockfd, const struct sockaddr *serv_addr,
 	fd_set *fdset;
 	struct timeval tv;
 	socklen_t optlen;
-	int fdsetsz, optval, rc, result = -1;
+	int optval, rc, result = -1;
 
 	if (timeout <= 0)
 		return (connect(sockfd, serv_addr, addrlen));
@@ -219,10 +215,8 @@ timeout_connect(int sockfd, const struct sockaddr *serv_addr,
 	if (errno != EINPROGRESS)
 		return (-1);
 
-	fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask);
-	fdset = (fd_set *)xmalloc(fdsetsz);
-
-	memset(fdset, 0, fdsetsz);
+	fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
+	    sizeof(fd_mask));
 	FD_SET(sockfd, fdset);
 	tv.tv_sec = timeout;
 	tv.tv_usec = 0;
@@ -947,8 +941,7 @@ ssh_put_password(char *password)
 		return;
 	}
 	size = roundup(strlen(password) + 1, 32);
-	padded = xmalloc(size);
-	memset(padded, 0, size);
+	padded = xcalloc(1, size);
 	strlcpy(padded, password, size);
 	packet_put_string(padded, size);
 	memset(padded, 0, size);