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netlink: Avoid left-over bytes in request on MTU configuration

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When nl_link() configures the MTU, it shouldn't send extra bytes,
otherwise we'll get a kernel warning:

  netlink: 4 bytes leftover after parsing attributes in process `pasta'.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Stefano Brivio 2022-02-23 10:50:09 +01:00
parent 08b7a2ec38
commit ed58ad1a59
1 changed files with 7 additions and 4 deletions
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11
netlink.c
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@ -479,13 +479,16 @@ next:
void nl_link(int ns, unsigned int ifi, void *mac, int up, int mtu)
{
int change = !MAC_IS_ZERO(mac) || up || mtu;
struct {
struct req_t {
struct nlmsghdr nlh;
struct ifinfomsg ifm;
struct rtattr rta;
union {
unsigned char mac[ETH_ALEN];
unsigned int mtu;
struct {
unsigned int mtu;
uint8_t end;
} mtu;
} set;
} req = {
.nlh.nlmsg_type = change ? RTM_NEWLINK : RTM_GETLINK,
@ -513,8 +516,8 @@ void nl_link(int ns, unsigned int ifi, void *mac, int up, int mtu)
}
if (mtu) {
req.nlh.nlmsg_len = sizeof(req);
req.set.mtu = mtu;
req.nlh.nlmsg_len = offsetof(struct req_t, set.mtu.end);
req.set.mtu.mtu = mtu;
req.rta.rta_type = IFLA_MTU;
req.rta.rta_len = RTA_LENGTH(sizeof(unsigned int));
nl_req(ns, buf, &req, req.nlh.nlmsg_len);