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.
Signed-off-by: Soenke Huster <soenke.huster@xxxxxxxxx>
---
v2: Spelling
drivers/net/wireless/mac80211_hwsim.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index 4fb8f68e5c3b..6bd9bd50071e 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -5436,6 +5436,10 @@ static int hwsim_virtio_handle_cmd(struct sk_buff *skb)
nlh = nlmsg_hdr(skb);
gnlh = nlmsg_data(nlh);
+
+ if (skb->len < nlh->nlmsg_len)
+ return -EINVAL;
+
err = genlmsg_parse(nlh, &hwsim_genl_family, tb, HWSIM_ATTR_MAX,
hwsim_genl_policy, NULL);
if (err) {
@@ -5478,7 +5482,8 @@ static void hwsim_virtio_rx_work(struct work_struct *work)
spin_unlock_irqrestore(&hwsim_virtio_lock, flags);
skb->data = skb->head;
- skb_set_tail_pointer(skb, len);
+ skb_reset_tail_pointer(skb);
+ skb_put(skb, len);
hwsim_virtio_handle_cmd(skb);
spin_lock_irqsave(&hwsim_virtio_lock, flags);
--
2.37.3
