From: Andrii Nakryiko <andriin@fb.com>
Date: Tue, 2 Jul 2019 15:16:20 +0000 (-0700)
Subject: libbpf: fix GCC8 warning for strncpy
X-Git-Tag: v5.1.20~175
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=925df79853ded6efc59f942927dd934ad9fb4129;p=thirdparty%2Fkernel%2Fstable.git

libbpf: fix GCC8 warning for strncpy

[ Upstream commit cdfc7f888c2a355b01308e97c6df108f1c2b64e8 ]

GCC8 started emitting warning about using strncpy with number of bytes
exactly equal destination size, which is generally unsafe, as can lead
to non-zero terminated string being copied. Use IFNAMSIZ - 1 as number
of bytes to ensure name is always zero-terminated.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Cc: Magnus Karlsson <magnus.karlsson@intel.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
index af5f310ecca1c..1fe0e1eec7383 100644
--- a/tools/lib/bpf/xsk.c
+++ b/tools/lib/bpf/xsk.c
@@ -336,7 +336,8 @@ static int xsk_get_max_queues(struct xsk_socket *xsk)
 
 	channels.cmd = ETHTOOL_GCHANNELS;
 	ifr.ifr_data = (void *)&channels;
-	strncpy(ifr.ifr_name, xsk->ifname, IFNAMSIZ);
+	strncpy(ifr.ifr_name, xsk->ifname, IFNAMSIZ - 1);
+	ifr.ifr_name[IFNAMSIZ - 1] = '\0';
 	err = ioctl(fd, SIOCETHTOOL, &ifr);
 	if (err && errno != EOPNOTSUPP) {
 		ret = -errno;