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, 53 insertions, 0 deletions

diff --git a/include/net/dsfield.h b/include/net/dsfield.h
new file mode 100644
index 000000000..a59a57ffc
--- /dev/null
+++ b/include/net/dsfield.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* include/net/dsfield.h - Manipulation of the Differentiated Services field */
+
+/* Written 1998-2000 by Werner Almesberger, EPFL ICA */
+
+
+#ifndef __NET_DSFIELD_H
+#define __NET_DSFIELD_H
+
+#include <linux/types.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <asm/byteorder.h>
+
+
+static inline __u8 ipv4_get_dsfield(const struct iphdr *iph)
+{
+	return iph->tos;
+}
+
+
+static inline __u8 ipv6_get_dsfield(const struct ipv6hdr *ipv6h)
+{
+	return ntohs(*(__force const __be16 *)ipv6h) >> 4;
+}
+
+
+static inline void ipv4_change_dsfield(struct iphdr *iph,__u8 mask,
+    __u8 value)
+{
+        __u32 check = ntohs((__force __be16)iph->check);
+	__u8 dsfield;
+
+	dsfield = (iph->tos & mask) | value;
+	check += iph->tos;
+	if ((check+1) >> 16) check = (check+1) & 0xffff;
+	check -= dsfield;
+	check += check >> 16; /* adjust carry */
+	iph->check = (__force __sum16)htons(check);
+	iph->tos = dsfield;
+}
+
+
+static inline void ipv6_change_dsfield(struct ipv6hdr *ipv6h,__u8 mask,
+    __u8 value)
+{
+	__be16 *p = (__force __be16 *)ipv6h;
+
+	*p = (*p & htons((((u16)mask << 4) | 0xf00f))) | htons((u16)value << 4);
+}
+
+
+#endif