* [PATCH] mt76: mt7615: Use after free in mt7615_mcu_set_bcn()
@ 2019-05-03 13:09 Dan Carpenter
2019-05-04 9:52 ` Lorenzo Bianconi
0 siblings, 1 reply; 2+ messages in thread
From: Dan Carpenter @ 2019-05-03 13:09 UTC (permalink / raw)
To: Felix Fietkau, Ryder Lee
Cc: Lorenzo Bianconi, Roy Luo, Kalle Valo, Matthias Brugger,
linux-wireless, linux-mediatek, kernel-janitors
We dereference "skb" when we assign:
req.pkt_len = cpu_to_le16(MT_TXD_SIZE + skb->len);
^^^^^^^^
So this patch just moves the dev_kfree_skb() down a bit to avoid the
use after free.
Fixes: 04b8e65922f6 ("mt76: add mac80211 driver for MT7615 PCIe-based chipsets")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
drivers/net/wireless/mediatek/mt76/mt7615/mcu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7615/mcu.c
index ea67c6022fe6..dc1301effa24 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7615/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7615/mcu.c
@@ -1270,7 +1270,6 @@ int mt7615_mcu_set_bcn(struct mt7615_dev *dev, struct ieee80211_vif *vif,
mt7615_mac_write_txwi(dev, (__le32 *)(req.pkt), skb, wcid, NULL,
0, NULL);
memcpy(req.pkt + MT_TXD_SIZE, skb->data, skb->len);
- dev_kfree_skb(skb);
req.omac_idx = mvif->omac_idx;
req.enable = en;
@@ -1281,6 +1280,7 @@ int mt7615_mcu_set_bcn(struct mt7615_dev *dev, struct ieee80211_vif *vif,
req.pkt_len = cpu_to_le16(MT_TXD_SIZE + skb->len);
req.tim_ie_pos = cpu_to_le16(MT_TXD_SIZE + tim_off);
+ dev_kfree_skb(skb);
skb = mt7615_mcu_msg_alloc(&req, sizeof(req));
return mt7615_mcu_msg_send(dev, skb, MCU_EXT_CMD_BCN_OFFLOAD,
--
2.18.0
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] mt76: mt7615: Use after free in mt7615_mcu_set_bcn()
2019-05-03 13:09 [PATCH] mt76: mt7615: Use after free in mt7615_mcu_set_bcn() Dan Carpenter
@ 2019-05-04 9:52 ` Lorenzo Bianconi
0 siblings, 0 replies; 2+ messages in thread
From: Lorenzo Bianconi @ 2019-05-04 9:52 UTC (permalink / raw)
To: Dan Carpenter
Cc: Felix Fietkau, Ryder Lee, Lorenzo Bianconi, Roy Luo, Kalle Valo,
Matthias Brugger, linux-wireless, linux-mediatek, kernel-janitors
[-- Attachment #1: Type: text/plain, Size: 1564 bytes --]
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
> We dereference "skb" when we assign:
>
> req.pkt_len = cpu_to_le16(MT_TXD_SIZE + skb->len);
> ^^^^^^^^
> So this patch just moves the dev_kfree_skb() down a bit to avoid the
> use after free.
>
> Fixes: 04b8e65922f6 ("mt76: add mac80211 driver for MT7615 PCIe-based chipsets")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> drivers/net/wireless/mediatek/mt76/mt7615/mcu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/mcu.c b/drivers/net/wireless/mediatek/mt76/mt7615/mcu.c
> index ea67c6022fe6..dc1301effa24 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7615/mcu.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7615/mcu.c
> @@ -1270,7 +1270,6 @@ int mt7615_mcu_set_bcn(struct mt7615_dev *dev, struct ieee80211_vif *vif,
> mt7615_mac_write_txwi(dev, (__le32 *)(req.pkt), skb, wcid, NULL,
> 0, NULL);
> memcpy(req.pkt + MT_TXD_SIZE, skb->data, skb->len);
> - dev_kfree_skb(skb);
>
> req.omac_idx = mvif->omac_idx;
> req.enable = en;
> @@ -1281,6 +1280,7 @@ int mt7615_mcu_set_bcn(struct mt7615_dev *dev, struct ieee80211_vif *vif,
> req.pkt_len = cpu_to_le16(MT_TXD_SIZE + skb->len);
> req.tim_ie_pos = cpu_to_le16(MT_TXD_SIZE + tim_off);
>
> + dev_kfree_skb(skb);
> skb = mt7615_mcu_msg_alloc(&req, sizeof(req));
>
> return mt7615_mcu_msg_send(dev, skb, MCU_EXT_CMD_BCN_OFFLOAD,
> --
> 2.18.0
>
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