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, 54 insertions, 0 deletions

diff --git a/lib/Kconfig.kmsan b/lib/Kconfig.kmsan
new file mode 100644
index 000000000..cae1ddcc1
--- /dev/null
+++ b/lib/Kconfig.kmsan
@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config HAVE_ARCH_KMSAN
+	bool
+
+config HAVE_KMSAN_COMPILER
+	def_bool $(cc-option,-fsanitize=kernel-memory)
+
+config KMSAN
+	bool "KMSAN: detector of uninitialized values use"
+	depends on HAVE_ARCH_KMSAN && HAVE_KMSAN_COMPILER
+	depends on DEBUG_KERNEL && !KASAN && !KCSAN
+	depends on !PREEMPT_RT
+	select STACKDEPOT
+	select STACKDEPOT_ALWAYS_INIT
+	help
+	  KernelMemorySanitizer (KMSAN) is a dynamic detector of uses of
+	  uninitialized values in the kernel. It is based on compiler
+	  instrumentation provided by Clang and thus requires Clang to build.
+
+	  An important note is that KMSAN is not intended for production use,
+	  because it drastically increases kernel memory footprint and slows
+	  the whole system down.
+
+	  See <file:Documentation/dev-tools/kmsan.rst> for more details.
+
+if KMSAN
+
+config KMSAN_CHECK_PARAM_RETVAL
+	bool "Check for uninitialized values passed to and returned from functions"
+	default y
+	help
+	  If the compiler supports -fsanitize-memory-param-retval, KMSAN will
+	  eagerly check every function parameter passed by value and every
+	  function return value.
+
+	  Disabling KMSAN_CHECK_PARAM_RETVAL will result in tracking shadow for
+	  function parameters and return values across function borders. This
+	  is a more relaxed mode, but it generates more instrumentation code and
+	  may potentially report errors in corner cases when non-instrumented
+	  functions call instrumented ones.
+
+config KMSAN_KUNIT_TEST
+	tristate "KMSAN integration test suite" if !KUNIT_ALL_TESTS
+	default KUNIT_ALL_TESTS
+	depends on TRACEPOINTS && KUNIT
+	help
+	  Test suite for KMSAN, testing various error detection scenarios,
+	  and checking that reports are correctly output to console.
+
+	  Say Y here if you want the test to be built into the kernel and run
+	  during boot; say M if you want the test to build as a module; say N
+	  if you are unsure.
+
+endif