From 10a2b430f8f06ae14b9590b6f6faa6b588ef0654 Mon Sep 17 00:00:00 2001 From: Bryam Vargas Date: Sat, 20 Jun 2026 21:45:18 -0500 Subject: [PATCH] wifi: mac80211_hwsim: clamp virtio RX length before skb_put hwsim_virtio_rx_work() passes the virtqueue used-ring length reported by the device straight to skb_put() on a fixed-size receive skb. A backend reporting a length larger than the skb tailroom drives skb_put() past the buffer end and hits skb_over_panic() -- a host-triggerable guest panic (denial of service). Clamp the length to the skb's available room before skb_put(). A conforming device never reports more than the posted buffer size, so valid frames are unaffected; a truncated over-report then fails the length/header checks in hwsim_virtio_handle_cmd() and is dropped, so truncating rather than dropping here cannot be turned into a parsing problem. Fixes: 5d44fe7c9808 ("mac80211_hwsim: add frame transmission support over virtio") Signed-off-by: Bryam Vargas Link: https://patch.msgid.link/20260620-b4-disp-474bee37-v1-1-1a4d37f3e2d4@proton.me Signed-off-by: Johannes Berg --- drivers/net/wireless/virtual/mac80211_hwsim_main.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/net/wireless/virtual/mac80211_hwsim_main.c b/drivers/net/wireless/virtual/mac80211_hwsim_main.c index 0dd8a6c85953..5c1718277599 100644 --- a/drivers/net/wireless/virtual/mac80211_hwsim_main.c +++ b/drivers/net/wireless/virtual/mac80211_hwsim_main.c @@ -7289,6 +7289,7 @@ static void hwsim_virtio_rx_work(struct work_struct *work) skb->data = skb->head; skb_reset_tail_pointer(skb); + len = min(len, skb_end_offset(skb)); skb_put(skb, len); hwsim_virtio_handle_cmd(skb);