From: Ido Schimmel <redacted>
Date: Mon, 29 Oct 2018 20:36:43 +0000

When an FDB entry is configured, the address is validated to have the
length of an Ethernet address, but the device for which the address is
configured can be of any type.

The above can result in the use of uninitialized memory when the address
is later compared against existing addresses since 'dev->addr_len' is
used and it may be greater than ETH_ALEN, as with ip6tnl devices.

Fix this by making sure that FDB entries are only configured for
Ethernet devices.

 ...

v2:
* Make error message more specific (David)

Fixes: 090096bf3db1 ("net: generic fdb support for drivers without ndo_fdb_<op>")
Signed-off-by: Ido Schimmel <redacted>
Reported-and-tested-by: syzbot+3a288d5f5530b901310e@syzkaller.appspotmail.com
Reported-and-tested-by: syzbot+d53ab4e92a1db04110ff@syzkaller.appspotmail.com
Cc: Vlad Yasevich <redacted>
Cc: David Ahern <redacted>

Applied and queued up for -stable, thanks.