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, 144 insertions, 0 deletions

diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c
new file mode 100644
index 000000000..8076ac410
--- /dev/null
+++ b/samples/kfifo/dma-example.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Sample fifo dma implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ */
+
+#include <linux/init.h>
+#include <linux/kfifo.h>
+#include <linux/module.h>
+#include <linux/scatterlist.h>
+#include <linux/dma-mapping.h>
+
+/*
+ * This module shows how to handle fifo dma operations.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	32
+
+static struct kfifo fifo;
+
+static int __init example_init(void)
+{
+	int			i;
+	unsigned int		ret;
+	unsigned int		nents;
+	struct scatterlist	sg[10];
+
+	printk(KERN_INFO "DMA fifo test start\n");
+
+	if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) {
+		printk(KERN_WARNING "error kfifo_alloc\n");
+		return -ENOMEM;
+	}
+
+	printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));
+
+	kfifo_in(&fifo, "test", 4);
+
+	for (i = 0; i != 9; i++)
+		kfifo_put(&fifo, i);
+
+	/* kick away first byte */
+	kfifo_skip(&fifo);
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	/*
+	 * Configure the kfifo buffer to receive data from DMA input.
+	 *
+	 *  .--------------------------------------.
+	 *  | 0 | 1 | 2 | ... | 12 | 13 | ... | 31 |
+	 *  |---|------------------|---------------|
+	 *   \_/ \________________/ \_____________/
+	 *    \          \                  \
+	 *     \          \_allocated data   \
+	 *      \_*free space*                \_*free space*
+	 *
+	 * We need two different SG entries: one for the free space area at the
+	 * end of the kfifo buffer (19 bytes) and another for the first free
+	 * byte at the beginning, after the kfifo_skip().
+	 */
+	sg_init_table(sg, ARRAY_SIZE(sg));
+	nents = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
+	printk(KERN_INFO "DMA sgl entries: %d\n", nents);
+	if (!nents) {
+		/* fifo is full and no sgl was created */
+		printk(KERN_WARNING "error kfifo_dma_in_prepare\n");
+		return -EIO;
+	}
+
+	/* receive data */
+	printk(KERN_INFO "scatterlist for receive:\n");
+	for (i = 0; i < nents; i++) {
+		printk(KERN_INFO
+		"sg[%d] -> "
+		"page %p offset 0x%.8x length 0x%.8x\n",
+			i, sg_page(&sg[i]), sg[i].offset, sg[i].length);
+
+		if (sg_is_last(&sg[i]))
+			break;
+	}
+
+	/* put here your code to setup and exectute the dma operation */
+	/* ... */
+
+	/* example: zero bytes received */
+	ret = 0;
+
+	/* finish the dma operation and update the received data */
+	kfifo_dma_in_finish(&fifo, ret);
+
+	/* Prepare to transmit data, example: 8 bytes */
+	nents = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
+	printk(KERN_INFO "DMA sgl entries: %d\n", nents);
+	if (!nents) {
+		/* no data was available and no sgl was created */
+		printk(KERN_WARNING "error kfifo_dma_out_prepare\n");
+		return -EIO;
+	}
+
+	printk(KERN_INFO "scatterlist for transmit:\n");
+	for (i = 0; i < nents; i++) {
+		printk(KERN_INFO
+		"sg[%d] -> "
+		"page %p offset 0x%.8x length 0x%.8x\n",
+			i, sg_page(&sg[i]), sg[i].offset, sg[i].length);
+
+		if (sg_is_last(&sg[i]))
+			break;
+	}
+
+	/* put here your code to setup and exectute the dma operation */
+	/* ... */
+
+	/* example: 5 bytes transmitted */
+	ret = 5;
+
+	/* finish the dma operation and update the transmitted data */
+	kfifo_dma_out_finish(&fifo, ret);
+
+	ret = kfifo_len(&fifo);
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	if (ret != 7) {
+		printk(KERN_WARNING "size mismatch: test failed");
+		return -EIO;
+	}
+	printk(KERN_INFO "test passed\n");
+
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	kfifo_free(&fifo);
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_DESCRIPTION("Sample fifo dma implementation");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");