From: Alexander Wetzel <alexander@xxxxxxxxxxxxxx> commit 746285cf81dc19502ab238249d75f5990bd2d231 upstream. Using not existing queues can panic the kernel with rtl8180/rtl8185 cards. Ignore the skb priority for those cards, they only have one tx queue. Pierre Asselin (pa@xxxxxxxxx) reported the kernel crash in the Gentoo forum: https://forums.gentoo.org/viewtopic-t-1147832-postdays-0-postorder-asc-start-25.html He also confirmed that this patch fixes the issue. In summary this happened: After updating wpa_supplicant from 2.9 to 2.10 the kernel crashed with a "divide error: 0000" when connecting to an AP. Control port tx now tries to use IEEE80211_AC_VO for the priority, which wpa_supplicants starts to use in 2.10. Since only the rtl8187se part of the driver supports QoS, the priority of the skb is set to IEEE80211_AC_BE (2) by mac80211 for rtl8180/rtl8185 cards. rtl8180 is then unconditionally reading out the priority and finally crashes on drivers/net/wireless/realtek/rtl818x/rtl8180/dev.c line 544 without this patch: idx = (ring->idx + skb_queue_len(&ring->queue)) % ring->entries "ring->entries" is zero for rtl8180/rtl8185 cards, tx_ring[2] never got initialized. Cc: stable@xxxxxxxxxxxxxxx Reported-by: pa@xxxxxxxxx Tested-by: pa@xxxxxxxxx Signed-off-by: Alexander Wetzel <alexander@xxxxxxxxxxxxxx> Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxx> Link: https://lore.kernel.org/r/20220422145228.7567-1-alexander@xxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/wireless/realtek/rtl818x/rtl8180/dev.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/drivers/net/wireless/realtek/rtl818x/rtl8180/dev.c +++ b/drivers/net/wireless/realtek/rtl818x/rtl8180/dev.c @@ -460,8 +460,10 @@ static void rtl8180_tx(struct ieee80211_ struct rtl8180_priv *priv = dev->priv; struct rtl8180_tx_ring *ring; struct rtl8180_tx_desc *entry; + unsigned int prio = 0; unsigned long flags; - unsigned int idx, prio, hw_prio; + unsigned int idx, hw_prio; + dma_addr_t mapping; u32 tx_flags; u8 rc_flags; @@ -470,7 +472,9 @@ static void rtl8180_tx(struct ieee80211_ /* do arithmetic and then convert to le16 */ u16 frame_duration = 0; - prio = skb_get_queue_mapping(skb); + /* rtl8180/rtl8185 only has one useable tx queue */ + if (dev->queues > IEEE80211_AC_BK) + prio = skb_get_queue_mapping(skb); ring = &priv->tx_ring[prio]; mapping = dma_map_single(&priv->pdev->dev, skb->data, skb->len,
