From: Jiri Bohac <jbohac@xxxxxxx>
[ Upstream commit 6c015a2256801597fadcbc11d287774c9c512fa5 ]
__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 ff92741270bf8b6e78aa885f166b68c7a67ab13a ("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: Jiri Bohac <jbohac@xxxxxxx>
Fixes: ff92741270bf ("net: introduce name_node struct to be used in hashlist")
Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/core/dev.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/net/core/dev.c b/net/core/dev.c
index 75ca6c6d01d6..dbc286fd2047 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1195,6 +1195,18 @@ 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)
--
2.30.1
