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, 68 insertions, 0 deletions

diff --git a/include/sound/seq_virmidi.h b/include/sound/seq_virmidi.h
new file mode 100644
index 000000000..359cb3633
--- /dev/null
+++ b/include/sound/seq_virmidi.h
@@ -0,0 +1,68 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef __SOUND_SEQ_VIRMIDI_H
+#define __SOUND_SEQ_VIRMIDI_H
+
+/*
+ *  Virtual Raw MIDI client on Sequencer
+ *  Copyright (c) 2000 by Takashi Iwai <tiwai@suse.de>,
+ *                        Jaroslav Kysela <perex@perex.cz>
+ */
+
+#include <sound/rawmidi.h>
+#include <sound/seq_midi_event.h>
+
+/*
+ * device file instance:
+ * This instance is created at each time the midi device file is
+ * opened.  Each instance has its own input buffer and MIDI parser
+ * (buffer), and is associated with the device instance.
+ */
+struct snd_virmidi {
+	struct list_head list;
+	int seq_mode;
+	int client;
+	int port;
+	bool trigger;
+	struct snd_midi_event *parser;
+	struct snd_seq_event event;
+	struct snd_virmidi_dev *rdev;
+	struct snd_rawmidi_substream *substream;
+	struct work_struct output_work;
+};
+
+#define SNDRV_VIRMIDI_SUBSCRIBE		(1<<0)
+#define SNDRV_VIRMIDI_USE		(1<<1)
+
+/*
+ * device record:
+ * Each virtual midi device has one device instance.  It contains
+ * common information and the linked-list of opened files, 
+ */
+struct snd_virmidi_dev {
+	struct snd_card *card;		/* associated card */
+	struct snd_rawmidi *rmidi;		/* rawmidi device */
+	int seq_mode;			/* SNDRV_VIRMIDI_XXX */
+	int device;			/* sequencer device */
+	int client;			/* created/attached client */
+	int port;			/* created/attached port */
+	unsigned int flags;		/* SNDRV_VIRMIDI_* */
+	struct rw_semaphore filelist_sem;
+	struct list_head filelist;
+};
+
+/* sequencer mode:
+ * ATTACH = input/output events from midi device are routed to the
+ *          attached sequencer port.  sequencer port is not created
+ *          by virmidi itself.
+ *          the input to rawmidi must be processed by passing the
+ *          incoming events via snd_virmidi_receive()
+ * DISPATCH = input/output events are routed to subscribers.
+ *            sequencer port is created in virmidi.
+ */
+#define SNDRV_VIRMIDI_SEQ_NONE		0
+#define SNDRV_VIRMIDI_SEQ_ATTACH	1
+#define SNDRV_VIRMIDI_SEQ_DISPATCH	2
+
+int snd_virmidi_new(struct snd_card *card, int device, struct snd_rawmidi **rrmidi);
+
+#endif /* __SOUND_SEQ_VIRMIDI */