Commit cb8ffde5 authored Jul 24, 2019 by Andrii Nakryiko Committed by Alexei Starovoitov Jul 25, 2019

libbpf: silence GCC8 warning about string truncation



Despite a proper NULL-termination after strncpy(..., ..., IFNAMSIZ - 1),
GCC8 still complains about *expected* string truncation:

  xsk.c:330:2: error: 'strncpy' output may be truncated copying 15 bytes
  from a string of length 15 [-Werror=stringop-truncation]
    strncpy(ifr.ifr_name, xsk->ifname, IFNAMSIZ - 1);

This patch gets rid of the issue altogether by using memcpy instead.
There is no performance regression, as strncpy will still copy and fill
all of the bytes anyway.

v1->v2:
- rebase against bpf tree.

Cc: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

parent decb705e

tools/lib/bpf/xsk.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -326,7 +326,7 @@ static int xsk_get_max_queues(struct xsk_socket *xsk)
		return -errno;

		ifr.ifr_data = (void *)&channels;
		strncpy(ifr.ifr_name, xsk->ifname, IFNAMSIZ - 1);
		memcpy(ifr.ifr_name, xsk->ifname, IFNAMSIZ - 1);
		ifr.ifr_name[IFNAMSIZ - 1] = '\0';
		err = ioctl(fd, SIOCETHTOOL, &ifr);
		if (err && errno != EOPNOTSUPP) {
		@@ -516,7 +516,7 @@ int xsk_socket__create(struct xsk_socket *xsk_ptr, const char ifname,
		err = -errno;
		goto out_socket;
		}
		strncpy(xsk->ifname, ifname, IFNAMSIZ - 1);
		memcpy(xsk->ifname, ifname, IFNAMSIZ - 1);
		xsk->ifname[IFNAMSIZ - 1] = '\0';

		err = xsk_set_xdp_socket_config(&xsk->config, usr_config);

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