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, 55 insertions, 0 deletions

diff --git a/Documentation/input/notifier.rst b/Documentation/input/notifier.rst
new file mode 100644
index 000000000..824379399
--- /dev/null
+++ b/Documentation/input/notifier.rst
@@ -0,0 +1,55 @@
+=================
+Keyboard notifier
+=================
+
+One can use register_keyboard_notifier to get called back on keyboard
+events (see kbd_keycode() function for details).  The passed structure is
+keyboard_notifier_param (see <linux/keyboard.h>):
+
+- 'vc' always provide the VC for which the keyboard event applies;
+- 'down' is 1 for a key press event, 0 for a key release;
+- 'shift' is the current modifier state, mask bit indexes are KG_*;
+- 'ledstate' is the current LED state;
+- 'value' depends on the type of event.
+
+- KBD_KEYCODE events are always sent before other events, value is the keycode.
+- KBD_UNBOUND_KEYCODE events are sent if the keycode is not bound to a keysym.
+  value is the keycode.
+- KBD_UNICODE events are sent if the keycode -> keysym translation produced a
+  unicode character. value is the unicode value.
+- KBD_KEYSYM events are sent if the keycode -> keysym translation produced a
+  non-unicode character. value is the keysym.
+- KBD_POST_KEYSYM events are sent after the treatment of non-unicode keysyms.
+  That permits one to inspect the resulting LEDs for instance.
+
+For each kind of event but the last, the callback may return NOTIFY_STOP in
+order to "eat" the event: the notify loop is stopped and the keyboard event is
+dropped.
+
+In a rough C snippet, we have::
+
+    kbd_keycode(keycode) {
+	...
+	params.value = keycode;
+	if (notifier_call_chain(KBD_KEYCODE,&params) == NOTIFY_STOP)
+	    || !bound) {
+		notifier_call_chain(KBD_UNBOUND_KEYCODE,&params);
+		return;
+	}
+
+	if (unicode) {
+		param.value = unicode;
+		if (notifier_call_chain(KBD_UNICODE,&params) == NOTIFY_STOP)
+			return;
+		emit unicode;
+		return;
+	}
+
+	params.value = keysym;
+	if (notifier_call_chain(KBD_KEYSYM,&params) == NOTIFY_STOP)
+		return;
+	apply keysym;
+	notifier_call_chain(KBD_POST_KEYSYM,&params);
+    }
+
+.. note:: This notifier is usually called from interrupt context.