[dpdk-dev] [PATCH 16/18] app: fix sprintf overrun bug

[Andy Green <andy@warmcat.com>]

/home/agreen/projects/dpdk/app/proc-info/main.c: In function ‘nic_xstats_display’:
/home/agreen/projects/dpdk/app/proc-info/main.c:495:45: error: ‘%s’ directive writing up to 255 bytes into a region of size between 165 and 232 [-Werror=format-overflow=]
    sprintf(buf, "PUTVAL %s/dpdkstat-port.%u/%s-%s N:%"
                                             ^~
     PRIu64"\n", host_id, port_id, counter_type,
                                   ~~~~~~~~~~~~
/home/agreen/projects/dpdk/app/proc-info/main.c:495:4: note: ‘sprintf’ output between 31 and 435 bytes into a destination of size 256
    sprintf(buf, "PUTVAL %s/dpdkstat-port.%u/%s-%s N:%"
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     PRIu64"\n", host_id, port_id, counter_type,
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     xstats_names[i].name, values[i]);
---
 app/proc-info/main.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/app/proc-info/main.c b/app/proc-info/main.c
index 539e13243..df46c235e 100644
--- a/app/proc-info/main.c
+++ b/app/proc-info/main.c
@@ -488,14 +488,19 @@ nic_xstats_display(uint16_t port_id)
 		if (enable_collectd_format) {
 			char counter_type[MAX_STRING_LEN];
 			char buf[MAX_STRING_LEN];
+			size_t n;
 
 			collectd_resolve_cnt_type(counter_type,
 						  sizeof(counter_type),
 						  xstats_names[i].name);
-			sprintf(buf, "PUTVAL %s/dpdkstat-port.%u/%s-%s N:%"
+			n = snprintf(buf, MAX_STRING_LEN,
+				"PUTVAL %s/dpdkstat-port.%u/%s-%s N:%"
 				PRIu64"\n", host_id, port_id, counter_type,
 				xstats_names[i].name, values[i]);
-			ret = write(stdout_fd, buf, strlen(buf));
+			buf[sizeof(buf) - 1] = '\0';
+			if (n > sizeof(buf) - 1)
+				n = sizeof(buf) - 1;
+			ret = write(stdout_fd, buf, n);
 			if (ret < 0)
 				goto err;
 		} else {