Commit 6c015a22 authored by Jiri Bohac's avatar Jiri Bohac Committed by David S. Miller
Browse files

net: check all name nodes in __dev_alloc_name 



__dev_alloc_name(), when supplied with a name containing '%d',
will search for the first available device number to generate a
unique device name.

Since commit ff927412 ("net:
introduce name_node struct to be used in hashlist") network
devices may have alternate names.  __dev_alloc_name() does take
these alternate names into account, possibly generating a name
that is already taken and failing with -ENFILE as a result.

This demonstrates the bug:

    # rmmod dummy 2>/dev/null
    # ip link property add dev lo altname dummy0
    # modprobe dummy numdummies=1
    modprobe: ERROR: could not insert 'dummy': Too many open files in system

Instead of creating a device named dummy1, modprobe fails.

Fix this by checking all the names in the d->name_node list, not just d->name.

Signed-off-by: default avatarJiri Bohac <jbohac@suse.cz>
Fixes: ff927412 ("net: introduce name_node struct to be used in hashlist")
Reviewed-by: default avatarJiri Pirko <jiri@nvidia.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 600cc3c9

net/core/dev.c

+12 −0
Original line number Diff line number Diff line
@@ -1184,6 +1184,18 @@ static int __dev_alloc_name(struct net *net, const char *name, char *buf) 
			return -ENOMEM;



		for_each_netdev(net, d) {

			struct netdev_name_node *name_node;

			list_for_each_entry(name_node, &d->name_node->list, list) {

				if (!sscanf(name_node->name, name, &i))

					continue;

				if (i < 0 || i >= max_netdevices)

					continue;



				/*  avoid cases where sscanf is not exact inverse of printf */

				snprintf(buf, IFNAMSIZ, name, i);

				if (!strncmp(buf, name_node->name, IFNAMSIZ))

					set_bit(i, inuse);

			}

			if (!sscanf(d->name, name, &i))

				continue;

			if (i < 0 || i >= max_netdevices)