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, 116 insertions, 0 deletions

diff --git a/lib/test_memcat_p.c b/lib/test_memcat_p.c
new file mode 100644
index 000000000..62f1633b3
--- /dev/null
+++ b/lib/test_memcat_p.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test cases for memcat_p() in lib/memcat_p.c
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+
+struct test_struct {
+	int		num;
+	unsigned int	magic;
+};
+
+#define MAGIC		0xf00ff00f
+/* Size of each of the NULL-terminated input arrays */
+#define INPUT_MAX	128
+/* Expected number of non-NULL elements in the output array */
+#define EXPECT		(INPUT_MAX * 2 - 2)
+
+static int __init test_memcat_p_init(void)
+{
+	struct test_struct **in0, **in1, **out, **p;
+	int err = -ENOMEM, i, r, total = 0;
+
+	in0 = kzalloc_objs(*in0, INPUT_MAX);
+	if (!in0)
+		return err;
+
+	in1 = kzalloc_objs(*in1, INPUT_MAX);
+	if (!in1)
+		goto err_free_in0;
+
+	for (i = 0, r = 1; i < INPUT_MAX - 1; i++) {
+		in0[i] = kmalloc_obj(**in0);
+		if (!in0[i])
+			goto err_free_elements;
+
+		in1[i] = kmalloc_obj(**in1);
+		if (!in1[i]) {
+			kfree(in0[i]);
+			goto err_free_elements;
+		}
+
+		/* lifted from test_sort.c */
+		r = (r * 725861) % 6599;
+		in0[i]->num = r;
+		in1[i]->num = -r;
+		in0[i]->magic = MAGIC;
+		in1[i]->magic = MAGIC;
+	}
+
+	in0[i] = in1[i] = NULL;
+
+	out = memcat_p(in0, in1);
+	if (!out)
+		goto err_free_all_elements;
+
+	err = -EINVAL;
+	for (i = 0, p = out; *p && (i < INPUT_MAX * 2 - 1); p++, i++) {
+		total += (*p)->num;
+
+		if ((*p)->magic != MAGIC) {
+			pr_err("test failed: wrong magic at %d: %u\n", i,
+			       (*p)->magic);
+			goto err_free_out;
+		}
+	}
+
+	if (total) {
+		pr_err("test failed: expected zero total, got %d\n", total);
+		goto err_free_out;
+	}
+
+	if (i != EXPECT) {
+		pr_err("test failed: expected output size %d, got %d\n",
+		       EXPECT, i);
+		goto err_free_out;
+	}
+
+	for (i = 0; i < INPUT_MAX - 1; i++)
+		if (out[i] != in0[i] || out[i + INPUT_MAX - 1] != in1[i]) {
+			pr_err("test failed: wrong element order at %d\n", i);
+			goto err_free_out;
+		}
+
+	err = 0;
+	pr_info("test passed\n");
+
+err_free_out:
+	kfree(out);
+err_free_all_elements:
+	i = INPUT_MAX;
+err_free_elements:
+	for (i--; i >= 0; i--) {
+		kfree(in1[i]);
+		kfree(in0[i]);
+	}
+
+	kfree(in1);
+err_free_in0:
+	kfree(in0);
+
+	return err;
+}
+
+static void __exit test_memcat_p_exit(void)
+{
+}
+
+module_init(test_memcat_p_init);
+module_exit(test_memcat_p_exit);
+
+MODULE_DESCRIPTION("Test cases for memcat_p() in lib/memcat_p.c");
+MODULE_LICENSE("GPL");