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libbpf: silence GCC8 warning about string truncation

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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>
This commit is contained in:
Andrii Nakryiko 2019-07-24 14:47:53 -07:00 committed by Alexei Starovoitov
parent decb705e01
commit cb8ffde569
1 changed files with 2 additions and 2 deletions
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4
tools/lib/bpf/xsk.c
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@ -326,7 +326,7 @@ static int xsk_get_max_queues(struct xsk_socket *xsk)
return -errno; return -errno;
ifr.ifr_data = (void *)&channels; 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'; ifr.ifr_name[IFNAMSIZ - 1] = '\0';
err = ioctl(fd, SIOCETHTOOL, &ifr); err = ioctl(fd, SIOCETHTOOL, &ifr);
if (err && errno != EOPNOTSUPP) { if (err && errno != EOPNOTSUPP) {
@ -516,7 +516,7 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname,
err = -errno; err = -errno;
goto out_socket; goto out_socket;
} }
strncpy(xsk->ifname, ifname, IFNAMSIZ - 1); memcpy(xsk->ifname, ifname, IFNAMSIZ - 1);
xsk->ifname[IFNAMSIZ - 1] = '\0'; xsk->ifname[IFNAMSIZ - 1] = '\0';
err = xsk_set_xdp_socket_config(&xsk->config, usr_config); err = xsk_set_xdp_socket_config(&xsk->config, usr_config);