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, 99 insertions, 0 deletions

diff --git a/lib/Kconfig.kfence b/lib/Kconfig.kfence
new file mode 100644
index 000000000..6fbbebec6
--- /dev/null
+++ b/lib/Kconfig.kfence
@@ -0,0 +1,99 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+config HAVE_ARCH_KFENCE
+	bool
+
+menuconfig KFENCE
+	bool "KFENCE: low-overhead sampling-based memory safety error detector"
+	depends on HAVE_ARCH_KFENCE
+	select STACKTRACE
+	select IRQ_WORK
+	help
+	  KFENCE is a low-overhead sampling-based detector of heap out-of-bounds
+	  access, use-after-free, and invalid-free errors. KFENCE is designed
+	  to have negligible cost to permit enabling it in production
+	  environments.
+
+	  See <file:Documentation/dev-tools/kfence.rst> for more details.
+
+	  Note that, KFENCE is not a substitute for explicit testing with tools
+	  such as KASAN. KFENCE can detect a subset of bugs that KASAN can
+	  detect, albeit at very different performance profiles. If you can
+	  afford to use KASAN, continue using KASAN, for example in test
+	  environments. If your kernel targets production use, and cannot
+	  enable KASAN due to its cost, consider using KFENCE.
+
+if KFENCE
+
+config KFENCE_SAMPLE_INTERVAL
+	int "Default sample interval in milliseconds"
+	default 100
+	help
+	  The KFENCE sample interval determines the frequency with which heap
+	  allocations will be guarded by KFENCE. May be overridden via boot
+	  parameter "kfence.sample_interval".
+
+	  Set this to 0 to disable KFENCE by default, in which case only
+	  setting "kfence.sample_interval" to a non-zero value enables KFENCE.
+
+config KFENCE_NUM_OBJECTS
+	int "Number of guarded objects available"
+	range 1 65535
+	default 255
+	help
+	  The number of guarded objects available. For each KFENCE object, 2
+	  pages are required; with one containing the object and two adjacent
+	  ones used as guard pages.
+
+config KFENCE_DEFERRABLE
+	bool "Use a deferrable timer to trigger allocations"
+	help
+	  Use a deferrable timer to trigger allocations. This avoids forcing
+	  CPU wake-ups if the system is idle, at the risk of a less predictable
+	  sample interval.
+
+	  Warning: The KUnit test suite fails with this option enabled - due to
+	  the unpredictability of the sample interval!
+
+	  Say N if you are unsure.
+
+config KFENCE_STATIC_KEYS
+	bool "Use static keys to set up allocations" if EXPERT
+	depends on JUMP_LABEL
+	help
+	  Use static keys (static branches) to set up KFENCE allocations. This
+	  option is only recommended when using very large sample intervals, or
+	  performance has carefully been evaluated with this option.
+
+	  Using static keys comes with trade-offs that need to be carefully
+	  evaluated given target workloads and system architectures. Notably,
+	  enabling and disabling static keys invoke IPI broadcasts, the latency
+	  and impact of which is much harder to predict than a dynamic branch.
+
+	  Say N if you are unsure.
+
+config KFENCE_STRESS_TEST_FAULTS
+	int "Stress testing of fault handling and error reporting" if EXPERT
+	default 0
+	help
+	  The inverse probability with which to randomly protect KFENCE object
+	  pages, resulting in spurious use-after-frees. The main purpose of
+	  this option is to stress test KFENCE with concurrent error reports
+	  and allocations/frees. A value of 0 disables stress testing logic.
+
+	  Only for KFENCE testing; set to 0 if you are not a KFENCE developer.
+
+config KFENCE_KUNIT_TEST
+	tristate "KFENCE integration test suite" if !KUNIT_ALL_TESTS
+	default KUNIT_ALL_TESTS
+	depends on TRACEPOINTS && KUNIT
+	help
+	  Test suite for KFENCE, testing various error detection scenarios with
+	  various allocation types, 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 # KFENCE