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wifi: rtl818x: rtl8187: Fix potential buffer underflow in rtl8187_rx_cb()

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The rtl8187_rx_cb() calculates the rx descriptor header address
by subtracting its size from the skb tail pointer.
However, it does not validate if the received packet
(skb->len from urb->actual_length) is large enough to contain this
header.

If a truncated packet is received, this will lead to a buffer
underflow, reading memory before the start of the skb data area,
and causing a kernel panic.

Add length checks for both rtl8187 and rtl8187b descriptor headers
before attempting to access them, dropping the packet cleanly if the
check fails.

Fixes: 6f7853f3cb ("rtl8187: change rtl8187_dev.c to support RTL8187B (part 2)")
Signed-off-by: Seungjin Bae <eeodqql09@gmail.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20251118013258.1789949-2-eeodqql09@gmail.com
This commit is contained in:
Seungjin Bae
2025-11-17 20:32:59 -05:00
committed by Ping-Ke Shih
parent c453d9c5bb
commit b647d2574e
1 changed files with 19 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c
View File

@@ -338,14 +338,16 @@ static void rtl8187_rx_cb(struct urb *urb)
spin_unlock_irqrestore(&priv->rx_queue.lock, f);
skb_put(skb, urb->actual_length);
if (unlikely(urb->status)) {
dev_kfree_skb_irq(skb);
return;
}
if (unlikely(urb->status))
goto free_skb;
if (!priv->is_rtl8187b) {
struct rtl8187_rx_hdr *hdr =
(typeof(hdr))(skb_tail_pointer(skb) - sizeof(*hdr));
struct rtl8187_rx_hdr *hdr;
if (skb->len < sizeof(struct rtl8187_rx_hdr))
goto free_skb;
hdr = (typeof(hdr))(skb_tail_pointer(skb) - sizeof(*hdr));
flags = le32_to_cpu(hdr->flags);
/* As with the RTL8187B below, the AGC is used to calculate
* signal strength. In this case, the scaling
@@ -355,8 +357,12 @@ static void rtl8187_rx_cb(struct urb *urb)
rx_status.antenna = (hdr->signal >> 7) & 1;
rx_status.mactime = le64_to_cpu(hdr->mac_time);
} else {
struct rtl8187b_rx_hdr *hdr =
(typeof(hdr))(skb_tail_pointer(skb) - sizeof(*hdr));
struct rtl8187b_rx_hdr *hdr;
if (skb->len < sizeof(struct rtl8187b_rx_hdr))
goto free_skb;
hdr = (typeof(hdr))(skb_tail_pointer(skb) - sizeof(*hdr));
/* The Realtek datasheet for the RTL8187B shows that the RX
* header contains the following quantities: signal quality,
* RSSI, AGC, the received power in dB, and the measured SNR.
@@ -409,6 +415,11 @@ static void rtl8187_rx_cb(struct urb *urb)
skb_unlink(skb, &priv->rx_queue);
dev_kfree_skb_irq(skb);
}
return;
free_skb:
dev_kfree_skb_irq(skb);
return;
}
static int rtl8187_init_urbs(struct ieee80211_hw *dev)