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authorPali Rohár <pali@kernel.org>2021-08-07 15:27:03 +0200
committerDavid S. Miller <davem@davemloft.net>2021-08-08 13:07:52 +0100
commit2459dcb96bcba94c08d6861f8a050185ff301672 (patch)
tree8bea657d5d8a440e369dea7ad0b72d68c615dd22 /drivers/net/ppp
parent2f5501a8f1cd795f36c0a8a3ed868ac53b6be802 (diff)
downloadlwn-2459dcb96bcba94c08d6861f8a050185ff301672.tar.gz
lwn-2459dcb96bcba94c08d6861f8a050185ff301672.zip
ppp: Fix generating ifname when empty IFLA_IFNAME is specified
IFLA_IFNAME is nul-term string which means that IFLA_IFNAME buffer can be larger than length of string which contains. Function __rtnl_newlink() generates new own ifname if either IFLA_IFNAME was not specified at all or userspace passed empty nul-term string. It is expected that if userspace does not specify ifname for new ppp netdev then kernel generates one in format "ppp<id>" where id matches to the ppp unit id which can be later obtained by PPPIOCGUNIT ioctl. And it works in this way if IFLA_IFNAME is not specified at all. But it does not work when IFLA_IFNAME is specified with empty string. So fix this logic also for empty IFLA_IFNAME in ppp_nl_newlink() function and correctly generates ifname based on ppp unit identifier if userspace did not provided preferred ifname. Without this patch when IFLA_IFNAME was specified with empty string then kernel created a new ppp interface in format "ppp<id>" but id did not match ppp unit id returned by PPPIOCGUNIT ioctl. In this case id was some number generated by __rtnl_newlink() function. Signed-off-by: Pali Rohár <pali@kernel.org> Fixes: bb8082f69138 ("ppp: build ifname using unit identifier for rtnl based devices") Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ppp')
-rw-r--r--drivers/net/ppp/ppp_generic.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 930e49ef15f6..b2b35ec37702 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -1306,7 +1306,7 @@ static int ppp_nl_newlink(struct net *src_net, struct net_device *dev,
* the PPP unit identifer as suffix (i.e. ppp<unit_id>). This allows
* userspace to infer the device name using to the PPPIOCGUNIT ioctl.
*/
- if (!tb[IFLA_IFNAME])
+ if (!tb[IFLA_IFNAME] || !nla_len(tb[IFLA_IFNAME]) || !*(char *)nla_data(tb[IFLA_IFNAME]))
conf.ifname_is_set = false;
err = ppp_dev_configure(src_net, dev, &conf);