staging: rtl8723bs: fix OOB read in rtw_action_frame_parse()grafted

rtw_action_frame_parse() takes a frame_len parameter but never
actually checks it before indexing into the frame body:

	const u8 *frame_body = frame + sizeof(struct ieee80211_hdr_3addr);
	...
	c = frame_body[0];
	...
	a = frame_body[1];

frame_body already points 24 bytes (sizeof(struct
ieee80211_hdr_3addr)) into frame, so reading frame_body[0] and
frame_body[1] requires frame_len >= 26. A management action frame
shorter than that (e.g. exactly 24 bytes, the minimum a malicious
peer can send) causes a 1-2 byte out-of-bounds read.

This is reachable from rtw_cfg80211_monitor_if_xmit_entry() and
cfg80211_rtw_mgmt_tx() in ioctl_cfg80211.c, both of which pass
attacker/user-influenced frame buffers and lengths straight through.

Add the missing length check before frame_body is dereferenced.

Fixes: 554c0a3abf216 ("staging: Add rtl8723bs sdio wifi driver")
Cc: stable@vger.kernel.org
Signed-off-by: Muhammad Bilal <meatuni001@gmail.com>
Link: https://patch.msgid.link/20260728125456.32359-3-meatuni001@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 205 insertions, 0 deletions

diff --git a/net/lapb/lapb_out.c b/net/lapb/lapb_out.c
new file mode 100644
index 000000000..a966d29c7
--- /dev/null
+++ b/net/lapb/lapb_out.c
@@ -0,0 +1,205 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	LAPB release 002
+ *
+ *	This code REQUIRES 2.1.15 or higher/ NET3.038
+ *
+ *	History
+ *	LAPB 001	Jonathan Naylor	Started Coding
+ *	LAPB 002	Jonathan Naylor	New timer architecture.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/in.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/inet.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <net/sock.h>
+#include <linux/uaccess.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <net/lapb.h>
+
+/*
+ *  This procedure is passed a buffer descriptor for an iframe. It builds
+ *  the rest of the control part of the frame and then writes it out.
+ */
+static void lapb_send_iframe(struct lapb_cb *lapb, struct sk_buff *skb, int poll_bit)
+{
+	unsigned char *frame;
+
+	if (!skb)
+		return;
+
+	if (lapb->mode & LAPB_EXTENDED) {
+		frame = skb_push(skb, 2);
+
+		frame[0] = LAPB_I;
+		frame[0] |= lapb->vs << 1;
+		frame[1] = poll_bit ? LAPB_EPF : 0;
+		frame[1] |= lapb->vr << 1;
+	} else {
+		frame = skb_push(skb, 1);
+
+		*frame = LAPB_I;
+		*frame |= poll_bit ? LAPB_SPF : 0;
+		*frame |= lapb->vr << 5;
+		*frame |= lapb->vs << 1;
+	}
+
+	lapb_dbg(1, "(%p) S%d TX I(%d) S%d R%d\n",
+		 lapb->dev, lapb->state, poll_bit, lapb->vs, lapb->vr);
+
+	lapb_transmit_buffer(lapb, skb, LAPB_COMMAND);
+}
+
+void lapb_kick(struct lapb_cb *lapb)
+{
+	struct sk_buff *skb, *skbn;
+	unsigned short modulus, start, end;
+
+	modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
+	start = !skb_peek(&lapb->ack_queue) ? lapb->va : lapb->vs;
+	end   = (lapb->va + lapb->window) % modulus;
+
+	if (!(lapb->condition & LAPB_PEER_RX_BUSY_CONDITION) &&
+	    start != end && skb_peek(&lapb->write_queue)) {
+		lapb->vs = start;
+
+		/*
+		 * Dequeue the frame and copy it.
+		 */
+		skb = skb_dequeue(&lapb->write_queue);
+
+		do {
+			skbn = skb_copy(skb, GFP_ATOMIC);
+			if (!skbn) {
+				skb_queue_head(&lapb->write_queue, skb);
+				break;
+			}
+
+			if (skb->sk)
+				skb_set_owner_w(skbn, skb->sk);
+
+			/*
+			 * Transmit the frame copy.
+			 */
+			lapb_send_iframe(lapb, skbn, LAPB_POLLOFF);
+
+			lapb->vs = (lapb->vs + 1) % modulus;
+
+			/*
+			 * Requeue the original data frame.
+			 */
+			skb_queue_tail(&lapb->ack_queue, skb);
+
+		} while (lapb->vs != end && (skb = skb_dequeue(&lapb->write_queue)) != NULL);
+
+		lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
+
+		if (!lapb_t1timer_running(lapb))
+			lapb_start_t1timer(lapb);
+	}
+}
+
+void lapb_transmit_buffer(struct lapb_cb *lapb, struct sk_buff *skb, int type)
+{
+	unsigned char *ptr;
+
+	ptr = skb_push(skb, 1);
+
+	if (lapb->mode & LAPB_MLP) {
+		if (lapb->mode & LAPB_DCE) {
+			if (type == LAPB_COMMAND)
+				*ptr = LAPB_ADDR_C;
+			if (type == LAPB_RESPONSE)
+				*ptr = LAPB_ADDR_D;
+		} else {
+			if (type == LAPB_COMMAND)
+				*ptr = LAPB_ADDR_D;
+			if (type == LAPB_RESPONSE)
+				*ptr = LAPB_ADDR_C;
+		}
+	} else {
+		if (lapb->mode & LAPB_DCE) {
+			if (type == LAPB_COMMAND)
+				*ptr = LAPB_ADDR_A;
+			if (type == LAPB_RESPONSE)
+				*ptr = LAPB_ADDR_B;
+		} else {
+			if (type == LAPB_COMMAND)
+				*ptr = LAPB_ADDR_B;
+			if (type == LAPB_RESPONSE)
+				*ptr = LAPB_ADDR_A;
+		}
+	}
+
+	lapb_dbg(2, "(%p) S%d TX %3ph\n", lapb->dev, lapb->state, skb->data);
+
+	if (!lapb_data_transmit(lapb, skb))
+		kfree_skb(skb);
+}
+
+void lapb_establish_data_link(struct lapb_cb *lapb)
+{
+	lapb->condition = 0x00;
+	lapb->n2count   = 0;
+
+	if (lapb->mode & LAPB_EXTENDED) {
+		lapb_dbg(1, "(%p) S%d TX SABME(1)\n", lapb->dev, lapb->state);
+		lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
+	} else {
+		lapb_dbg(1, "(%p) S%d TX SABM(1)\n", lapb->dev, lapb->state);
+		lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
+	}
+
+	lapb_start_t1timer(lapb);
+	lapb_stop_t2timer(lapb);
+}
+
+void lapb_enquiry_response(struct lapb_cb *lapb)
+{
+	lapb_dbg(1, "(%p) S%d TX RR(1) R%d\n",
+		 lapb->dev, lapb->state, lapb->vr);
+
+	lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE);
+
+	lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
+}
+
+void lapb_timeout_response(struct lapb_cb *lapb)
+{
+	lapb_dbg(1, "(%p) S%d TX RR(0) R%d\n",
+		 lapb->dev, lapb->state, lapb->vr);
+	lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE);
+
+	lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
+}
+
+void lapb_check_iframes_acked(struct lapb_cb *lapb, unsigned short nr)
+{
+	if (lapb->vs == nr) {
+		lapb_frames_acked(lapb, nr);
+		lapb_stop_t1timer(lapb);
+		lapb->n2count = 0;
+	} else if (lapb->va != nr) {
+		lapb_frames_acked(lapb, nr);
+		lapb_start_t1timer(lapb);
+	}
+}
+
+void lapb_check_need_response(struct lapb_cb *lapb, int type, int pf)
+{
+	if (type == LAPB_COMMAND && pf)
+		lapb_enquiry_response(lapb);
+}