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>

2 files changed, 65 insertions, 0 deletions

diff --git a/samples/trace_printk/Makefile b/samples/trace_printk/Makefile
new file mode 100644
index 000000000..c0df36167
--- /dev/null
+++ b/samples/trace_printk/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-only
+# builds a module that calls various trace_printk routines
+# then to use one (as root):  insmod <module_name.ko>
+
+# This module can also be used to test the trace_printk code.
+
+obj-$(CONFIG_SAMPLE_TRACE_PRINTK) += trace-printk.o
diff --git a/samples/trace_printk/trace-printk.c b/samples/trace_printk/trace-printk.c
new file mode 100644
index 000000000..cfc159580
--- /dev/null
+++ b/samples/trace_printk/trace-printk.c
@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/module.h>
+#include <linux/kthread.h>
+#include <linux/irq_work.h>
+
+/* Must not be static to force gcc to consider these non constant */
+char *trace_printk_test_global_str =
+	"This is a dynamic string that will use trace_puts\n";
+
+char *trace_printk_test_global_str_irq =
+	"(irq) This is a dynamic string that will use trace_puts\n";
+
+char *trace_printk_test_global_str_fmt =
+	"%sThis is a %s that will use trace_printk\n";
+
+static struct irq_work irqwork;
+
+static void trace_printk_irq_work(struct irq_work *work)
+{
+	trace_printk("(irq) This is a static string that will use trace_bputs\n");
+	trace_printk(trace_printk_test_global_str_irq);
+
+	trace_printk("(irq) This is a %s that will use trace_bprintk()\n",
+		     "static string");
+
+	trace_printk(trace_printk_test_global_str_fmt,
+		     "(irq) ", "dynamic string");
+}
+
+static int __init trace_printk_init(void)
+{
+	init_irq_work(&irqwork, trace_printk_irq_work);
+
+	trace_printk("This is a static string that will use trace_bputs\n");
+	trace_printk(trace_printk_test_global_str);
+
+	/* Kick off printing in irq context */
+	irq_work_queue(&irqwork);
+	irq_work_sync(&irqwork);
+
+	trace_printk("This is a %s that will use trace_bprintk()\n",
+		     "static string");
+
+	trace_printk(trace_printk_test_global_str_fmt, "", "dynamic string");
+
+	return 0;
+}
+
+static void __exit trace_printk_exit(void)
+{
+}
+
+module_init(trace_printk_init);
+module_exit(trace_printk_exit);
+
+MODULE_AUTHOR("Steven Rostedt");
+MODULE_DESCRIPTION("trace-printk");
+MODULE_LICENSE("GPL");