Mitigate Baron SameEdit (CVE-2021-3156) vulnerability

centos 7
format weakness #7


Weakness Breakdown


A format string exploit occurs when the data of an input string is evaluated as a command by the program. This class of attacks is very similar to buffer overflows since an attacker could execute code, read the stack or cause new behaviors that compromise security. Learn more about format string attacks on OWASP attack index.

Warning code(s):

If format strings can be influenced by an attacker, they can be exploited, and note that sprintf variations do not always 0-terminate.

File Name:



The highlighted line of code below is the trigger point of this particular Centos 7 format weakness.

 int br_set_ageing_time(const char *br, struct timeval *tv)
	return br_set(br, "ageing_time", __tv_to_jiffies(tv),

int br_set_stp_state(const char *br, int stp_state)
	return br_set(br, "stp_state", stp_state, BRCTL_SET_BRIDGE_STP_STATE);

int br_set_bridge_priority(const char *br, int bridge_priority)
	return br_set(br, "priority", bridge_priority, 

static int port_set(const char *bridge, const char *ifname, 
		    const char *name, unsigned long value, 
		    unsigned long oldcode)
	int ret;
	char path[SYSFS_PATH_MAX];

	snprintf(path, SYSFS_PATH_MAX, SYSFS_CLASS_NET "%s/brport/%s", ifname, name);

	if ((ret = set_sysfs(path, value)) < 0) {
		int index = get_portno(bridge, ifname);

		if (index < 0)
			ret = index;
		else {
			struct ifreq ifr;
			unsigned long args[4] = { oldcode, index, value, 0 };
			strncpy(ifr.ifr_name, bridge, IFNAMSIZ);
			ifr.ifr_data = (char *) &args;
			ret = ioctl(br_socket_fd, SIOCDEVPRIVATE, &ifr);

	return ret < 0 ? errno : 0;

int br_set_port_priority(const char *bridge, const char *port, int priority)
	return port_set(bridge, port, "priority", priority, BRCTL_SET_PORT_PRIORITY);

int br_set_path_cost(const char *bridge, const char *port, int cost) 

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