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, 50 insertions, 0 deletions

diff --git a/rust/ffi.rs b/rust/ffi.rs
new file mode 100644
index 000000000..f961e9728
--- /dev/null
+++ b/rust/ffi.rs
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Foreign function interface (FFI) types.
+//!
+//! This crate provides mapping from C primitive types to Rust ones.
+//!
+//! The Rust [`core`] crate provides [`core::ffi`], which maps integer types to the platform default
+//! C ABI. The kernel does not use [`core::ffi`], so it can customise the mapping that deviates from
+//! the platform default.
+
+#![no_std]
+
+macro_rules! alias {
+    ($($name:ident = $ty:ty;)*) => {$(
+        #[allow(non_camel_case_types, missing_docs)]
+        pub type $name = $ty;
+
+        // Check size compatibility with `core`.
+        const _: () = assert!(
+            ::core::mem::size_of::<$name>() == ::core::mem::size_of::<::core::ffi::$name>()
+        );
+    )*}
+}
+
+alias! {
+    // `core::ffi::c_char` is either `i8` or `u8` depending on architecture. In the kernel, we use
+    // `-funsigned-char` so it's always mapped to `u8`.
+    c_char = u8;
+
+    c_schar = i8;
+    c_uchar = u8;
+
+    c_short = i16;
+    c_ushort = u16;
+
+    c_int = i32;
+    c_uint = u32;
+
+    // In the kernel, `intptr_t` is defined to be `long` in all platforms, so we can map the type to
+    // `isize`.
+    c_long = isize;
+    c_ulong = usize;
+
+    c_longlong = i64;
+    c_ulonglong = u64;
+}
+
+pub use core::ffi::c_void;
+
+pub use core::ffi::CStr;