An invalid packet with a length shorter than the specified length in the
netlink header can lead to use-after-frees and slab-out-of-bounds in the
processing of the netlink attributes, such as the following:
BUG: KASAN: slab-out-of-bounds in __nla_validate_parse+0x1258/0x2010
Read of size 2 at addr ffff88800ac7952c by task kworker/0:1/12
Workqueue: events hwsim_virtio_rx_work
Call Trace:
<TASK>
dump_stack_lvl+0x45/0x5d
print_report.cold+0x5e/0x5e5
kasan_report+0xb1/0x1c0
__nla_validate_parse+0x1258/0x2010
__nla_parse+0x22/0x30
hwsim_virtio_handle_cmd.isra.0+0x13f/0x2d0
hwsim_virtio_rx_work+0x1b2/0x370
process_one_work+0x8df/0x1530
worker_thread+0x575/0x11a0
kthread+0x29d/0x340
ret_from_fork+0x22/0x30
</TASK>
Discarding packets with an invalid length solves this.
Therefore, skb->len must be set at reception.
Change-Id: Ieaeb9a4c62d3beede274881a7c2722c6c6f477b6
Signed-off-by: Soenke Huster <soenke.huster@eknoes.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
8c0427842a