linux-kernel - [PATCH net-next 4/4] veth: Fix -Wformat-truncation

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Date:   Thu, 21 Feb 2019 20:09:29 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, Florian Fainelli <f.fainelli@...il.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Toshiaki Makita <makita.toshiaki@....ntt.co.jp>,
        David Ahern <dsahern@...il.com>,
        Michael Walle <michael@...le.cc>,
        Li RongQing <lirongqing@...du.com>,
        linux-kernel@...r.kernel.org (open list),
        xdp-newbies@...r.kernel.org (open list:XDP (eXpress Data Path))
Subject: [PATCH net-next 4/4] veth: Fix -Wformat-truncation

Provide a precision hint to snprintf() in order to eliminate a
-Wformat-truncation warning provided below. A maximum of 11 characters
is allowed to reach a maximum of 32 - 1 characters given a possible
maximum value of queues using up to UINT_MAX which occupies 10
characters. Incidentally 11 is the number of characters for
"xdp_packets" which is the largest string we append.

drivers/net/veth.c: In function 'veth_get_strings':
drivers/net/veth.c:118:47: warning: '%s' directive output may be
truncated writing up to 31 bytes into a region of size between 12 and 21
[-Wformat-truncation=]
     snprintf(p, ETH_GSTRING_LEN, "rx_queue_%u_%s",
                                               ^~
drivers/net/veth.c:118:5: note: 'snprintf' output between 12 and 52
bytes into a destination of size 32
     snprintf(p, ETH_GSTRING_LEN, "rx_queue_%u_%s",
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
       i, veth_rq_stats_desc[j].desc);
       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
---
 drivers/net/veth.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index fbf890ebbeae..569e87a51a33 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -115,7 +115,8 @@ static void veth_get_strings(struct net_device *dev, u32 stringset, u8 *buf)
 		p += sizeof(ethtool_stats_keys);
 		for (i = 0; i < dev->real_num_rx_queues; i++) {
 			for (j = 0; j < VETH_RQ_STATS_LEN; j++) {
-				snprintf(p, ETH_GSTRING_LEN, "rx_queue_%u_%s",
+				snprintf(p, ETH_GSTRING_LEN,
+					 "rx_queue_%u_%.11s",
 					 i, veth_rq_stats_desc[j].desc);
 				p += ETH_GSTRING_LEN;
 			}
-- 
2.19.1