Re: [PATCH] net: check all name nodes in __dev_alloc_name

Thu, Mar 18, 2021 at 04:42:53AM CET, jbohac@suse.cz wrote:

__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 <redacted>
Fixes: ff92741270bf ("net: introduce name_node struct to be used in hashlist")

Reviewed-by: Jiri Pirko <redacted>

Thanks!