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, 128 insertions, 0 deletions

diff --git a/samples/hid/hid_mouse.bpf.c b/samples/hid/hid_mouse.bpf.c
new file mode 100644
index 000000000..f7f722dcf
--- /dev/null
+++ b/samples/hid/hid_mouse.bpf.c
@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "hid_bpf_helpers.h"
+
+static int hid_y_event(struct hid_bpf_ctx *hctx)
+{
+	s16 y;
+	__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 9 /* size */);
+
+	if (!data)
+		return 0; /* EPERM check */
+
+	bpf_printk("event: size: %d", hctx->size);
+	bpf_printk("incoming event: %02x %02x %02x",
+		   data[0],
+		   data[1],
+		   data[2]);
+	bpf_printk("                %02x %02x %02x",
+		   data[3],
+		   data[4],
+		   data[5]);
+	bpf_printk("                %02x %02x %02x",
+		   data[6],
+		   data[7],
+		   data[8]);
+
+	y = data[3] | (data[4] << 8);
+
+	y = -y;
+
+	data[3] = y & 0xFF;
+	data[4] = (y >> 8) & 0xFF;
+
+	bpf_printk("modified event: %02x %02x %02x",
+		   data[0],
+		   data[1],
+		   data[2]);
+	bpf_printk("                %02x %02x %02x",
+		   data[3],
+		   data[4],
+		   data[5]);
+	bpf_printk("                %02x %02x %02x",
+		   data[6],
+		   data[7],
+		   data[8]);
+
+	return 0;
+}
+
+static int hid_x_event(struct hid_bpf_ctx *hctx)
+{
+	s16 x;
+	__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 9 /* size */);
+
+	if (!data)
+		return 0; /* EPERM check */
+
+	x = data[1] | (data[2] << 8);
+
+	x = -x;
+
+	data[1] = x & 0xFF;
+	data[2] = (x >> 8) & 0xFF;
+	return 0;
+}
+
+SEC("struct_ops/hid_device_event")
+int BPF_PROG(hid_event, struct hid_bpf_ctx *hctx, enum hid_report_type type)
+{
+	int ret = hid_y_event(hctx);
+
+	if (ret)
+		return ret;
+
+	return hid_x_event(hctx);
+}
+
+
+SEC("struct_ops/hid_rdesc_fixup")
+int BPF_PROG(hid_rdesc_fixup, struct hid_bpf_ctx *hctx)
+{
+	__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 4096 /* size */);
+
+	if (!data)
+		return 0; /* EPERM check */
+
+	bpf_printk("rdesc: %02x %02x %02x",
+		   data[0],
+		   data[1],
+		   data[2]);
+	bpf_printk("       %02x %02x %02x",
+		   data[3],
+		   data[4],
+		   data[5]);
+	bpf_printk("       %02x %02x %02x ...",
+		   data[6],
+		   data[7],
+		   data[8]);
+
+	/*
+	 * The original report descriptor contains:
+	 *
+	 * 0x05, 0x01,                    //   Usage Page (Generic Desktop)      30
+	 * 0x16, 0x01, 0x80,              //   Logical Minimum (-32767)          32
+	 * 0x26, 0xff, 0x7f,              //   Logical Maximum (32767)           35
+	 * 0x09, 0x30,                    //   Usage (X)                         38
+	 * 0x09, 0x31,                    //   Usage (Y)                         40
+	 *
+	 * So byte 39 contains Usage X and byte 41 Usage Y.
+	 *
+	 * We simply swap the axes here.
+	 */
+	data[39] = 0x31;
+	data[41] = 0x30;
+
+	return 0;
+}
+
+SEC(".struct_ops.link")
+struct hid_bpf_ops mouse_invert = {
+	.hid_rdesc_fixup = (void *)hid_rdesc_fixup,
+	.hid_device_event = (void *)hid_event,
+};
+
+char _license[] SEC("license") = "GPL";