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, 36 insertions, 0 deletions

diff --git a/tools/include/nolibc/assert.h b/tools/include/nolibc/assert.h
new file mode 100644
index 000000000..84ff8ad9a
--- /dev/null
+++ b/tools/include/nolibc/assert.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * Assert for NOLIBC
+ * Copyright (C) 2026 Thomas Weißschuh <linux@weissschuh.net>
+ */
+
+/* make sure to include all global symbols */
+#include "nolibc.h"
+
+#ifndef _NOLIBC_ASSERT_H
+#define _NOLIBC_ASSERT_H
+
+#include "errno.h"
+#include "stdio.h"
+#include "stdlib.h"
+
+#endif /* _NOLIBC_ASSERT_H */
+
+/* NDEBUG needs to be evaluated on *each* inclusion */
+#ifdef assert
+#undef assert
+#endif
+
+#ifndef NDEBUG
+#define assert(expr)									\
+({											\
+	if (!(expr)) {									\
+		fprintf(stderr, "%s: %s:%d: %s: Assertion `%s' failed.\n",		\
+			program_invocation_short_name, __FILE__, __LINE__, __func__,	\
+			#expr);								\
+		abort();								\
+	}										\
+})
+#else
+#define assert(expr) ((void)0)
+#endif