From 8c0427842aaef161a38ac83b7e8d8fe050b4be04 Mon Sep 17 00:00:00 2001 From: Soenke Huster Date: Fri, 2 Sep 2022 10:19:58 +0200 Subject: [PATCH] wifi: mac80211_hwsim: check length for virtio packets 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: 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 Discarding packets with an invalid length solves this. Therefore, skb->len must be set at reception. Change-Id: Ieaeb9a4c62d3beede274881a7c2722c6c6f477b6 Signed-off-by: Soenke Huster Signed-off-by: Johannes Berg --- 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 6e55f15..1f301a5 100644 --- a/drivers/net/wireless/mac80211_hwsim.c +++ b/drivers/net/wireless/mac80211_hwsim.c @@ -5060,6 +5060,10 @@ 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) { @@ -5102,7 +5106,8 @@ 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); -- 2.7.4