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, 83 insertions, 0 deletions

diff --git a/lib/decompress.c b/lib/decompress.c
new file mode 100644
index 000000000..778547158
--- /dev/null
+++ b/lib/decompress.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * decompress.c
+ *
+ * Detect the decompression method based on magic number
+ */
+
+#include <linux/decompress/generic.h>
+
+#include <linux/decompress/bunzip2.h>
+#include <linux/decompress/unlzma.h>
+#include <linux/decompress/unxz.h>
+#include <linux/decompress/inflate.h>
+#include <linux/decompress/unlzo.h>
+#include <linux/decompress/unlz4.h>
+#include <linux/decompress/unzstd.h>
+
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/init.h>
+#include <linux/printk.h>
+
+#ifndef CONFIG_DECOMPRESS_GZIP
+# define gunzip NULL
+#endif
+#ifndef CONFIG_DECOMPRESS_BZIP2
+# define bunzip2 NULL
+#endif
+#ifndef CONFIG_DECOMPRESS_LZMA
+# define unlzma NULL
+#endif
+#ifndef CONFIG_DECOMPRESS_XZ
+# define unxz NULL
+#endif
+#ifndef CONFIG_DECOMPRESS_LZO
+# define unlzo NULL
+#endif
+#ifndef CONFIG_DECOMPRESS_LZ4
+# define unlz4 NULL
+#endif
+#ifndef CONFIG_DECOMPRESS_ZSTD
+# define unzstd NULL
+#endif
+
+struct compress_format {
+	unsigned char magic[2];
+	const char *name;
+	decompress_fn decompressor;
+};
+
+static const struct compress_format compressed_formats[] __initconst = {
+	{ .magic = {0x1f, 0x8b}, .name = "gzip", .decompressor = gunzip },
+	{ .magic = {0x1f, 0x9e}, .name = "gzip", .decompressor = gunzip },
+	{ .magic = {0x42, 0x5a}, .name = "bzip2", .decompressor = bunzip2 },
+	{ .magic = {0x5d, 0x00}, .name = "lzma", .decompressor = unlzma },
+	{ .magic = {0xfd, 0x37}, .name = "xz", .decompressor = unxz },
+	{ .magic = {0x89, 0x4c}, .name = "lzo", .decompressor = unlzo },
+	{ .magic = {0x02, 0x21}, .name = "lz4", .decompressor = unlz4 },
+	{ .magic = {0x28, 0xb5}, .name = "zstd", .decompressor = unzstd },
+	{ /* sentinel */ }
+};
+
+decompress_fn __init decompress_method(const unsigned char *inbuf, long len,
+				const char **name)
+{
+	const struct compress_format *cf;
+
+	if (len < 2) {
+		if (name)
+			*name = NULL;
+		return NULL;	/* Need at least this much... */
+	}
+
+	pr_debug("Compressed data magic: %#.2x %#.2x\n", inbuf[0], inbuf[1]);
+
+	for (cf = compressed_formats; cf->name; cf++)
+		if (!memcmp(inbuf, cf->magic, 2))
+			break;
+
+	if (name)
+		*name = cf->name;
+	return cf->decompressor;
+}