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, 201 insertions, 0 deletions

diff --git a/tools/lib/api/io.h b/tools/lib/api/io.h
new file mode 100644
index 000000000..1731996b2
--- /dev/null
+++ b/tools/lib/api/io.h
@@ -0,0 +1,201 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Lightweight buffered reading library.
+ *
+ * Copyright 2019 Google LLC.
+ */
+#ifndef __API_IO__
+#define __API_IO__
+
+#include <errno.h>
+#include <poll.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <linux/types.h>
+
+struct io {
+	/* File descriptor being read/ */
+	int fd;
+	/* Size of the read buffer. */
+	unsigned int buf_len;
+	/* Pointer to storage for buffering read. */
+	char *buf;
+	/* End of the storage. */
+	char *end;
+	/* Currently accessed data pointer. */
+	char *data;
+	/* Read timeout, 0 implies no timeout. */
+	int timeout_ms;
+	/* Set true on when the end of file on read error. */
+	bool eof;
+};
+
+static inline void io__init(struct io *io, int fd,
+			    char *buf, unsigned int buf_len)
+{
+	io->fd = fd;
+	io->buf_len = buf_len;
+	io->buf = buf;
+	io->end = buf;
+	io->data = buf;
+	io->timeout_ms = 0;
+	io->eof = false;
+}
+
+/* Read from fd filling the buffer. Called when io->data == io->end. */
+static inline int io__fill_buffer(struct io *io)
+{
+	ssize_t n;
+
+	if (io->eof)
+		return -1;
+
+	if (io->timeout_ms != 0) {
+		struct pollfd pfds[] = {
+			{
+				.fd = io->fd,
+				.events = POLLIN,
+			},
+		};
+
+		n = poll(pfds, 1, io->timeout_ms);
+		if (n == 0)
+			errno = ETIMEDOUT;
+		if (n > 0 && !(pfds[0].revents & POLLIN)) {
+			errno = EIO;
+			n = -1;
+		}
+		if (n <= 0) {
+			io->eof = true;
+			return -1;
+		}
+	}
+	n = read(io->fd, io->buf, io->buf_len);
+
+	if (n <= 0) {
+		io->eof = true;
+		return -1;
+	}
+	io->data = &io->buf[0];
+	io->end = &io->buf[n];
+	return 0;
+}
+
+/* Reads one character from the "io" file with similar semantics to fgetc. */
+static inline int io__get_char(struct io *io)
+{
+	if (io->data == io->end) {
+		int ret = io__fill_buffer(io);
+
+		if (ret)
+			return ret;
+	}
+	return *io->data++;
+}
+
+/* Read a hexadecimal value with no 0x prefix into the out argument hex. If the
+ * first character isn't hexadecimal returns -2, io->eof returns -1, otherwise
+ * returns the character after the hexadecimal value which may be -1 for eof.
+ * If the read value is larger than a u64 the high-order bits will be dropped.
+ */
+static inline int io__get_hex(struct io *io, __u64 *hex)
+{
+	bool first_read = true;
+
+	*hex = 0;
+	while (true) {
+		int ch = io__get_char(io);
+
+		if (ch < 0)
+			return ch;
+		if (ch >= '0' && ch <= '9')
+			*hex = (*hex << 4) | (ch - '0');
+		else if (ch >= 'a' && ch <= 'f')
+			*hex = (*hex << 4) | (ch - 'a' + 10);
+		else if (ch >= 'A' && ch <= 'F')
+			*hex = (*hex << 4) | (ch - 'A' + 10);
+		else if (first_read)
+			return -2;
+		else
+			return ch;
+		first_read = false;
+	}
+}
+
+/* Read a positive decimal value with out argument dec. If the first character
+ * isn't a decimal returns -2, io->eof returns -1, otherwise returns the
+ * character after the decimal value which may be -1 for eof. If the read value
+ * is larger than a u64 the high-order bits will be dropped.
+ */
+static inline int io__get_dec(struct io *io, __u64 *dec)
+{
+	bool first_read = true;
+
+	*dec = 0;
+	while (true) {
+		int ch = io__get_char(io);
+
+		if (ch < 0)
+			return ch;
+		if (ch >= '0' && ch <= '9')
+			*dec = (*dec * 10) + ch - '0';
+		else if (first_read)
+			return -2;
+		else
+			return ch;
+		first_read = false;
+	}
+}
+
+/* Read up to and including the first delim. */
+static inline ssize_t io__getdelim(struct io *io, char **line_out, size_t *line_len_out, int delim)
+{
+	char buf[128];
+	int buf_pos = 0;
+	char *line = NULL, *temp;
+	size_t line_len = 0;
+	int ch = 0;
+
+	/* TODO: reuse previously allocated memory. */
+	free(*line_out);
+	while (ch != delim) {
+		ch = io__get_char(io);
+
+		if (ch < 0)
+			break;
+
+		if (buf_pos == sizeof(buf)) {
+			temp = realloc(line, line_len + sizeof(buf));
+			if (!temp)
+				goto err_out;
+			line = temp;
+			memcpy(&line[line_len], buf, sizeof(buf));
+			line_len += sizeof(buf);
+			buf_pos = 0;
+		}
+		buf[buf_pos++] = (char)ch;
+	}
+	temp = realloc(line, line_len + buf_pos + 1);
+	if (!temp)
+		goto err_out;
+	line = temp;
+	memcpy(&line[line_len], buf, buf_pos);
+	line[line_len + buf_pos] = '\0';
+	line_len += buf_pos;
+	*line_out = line;
+	*line_len_out = line_len;
+	return line_len;
+err_out:
+	free(line);
+	*line_out = NULL;
+	*line_len_out = 0;
+	return -ENOMEM;
+}
+
+static inline ssize_t io__getline(struct io *io, char **line_out, size_t *line_len_out)
+{
+	return io__getdelim(io, line_out, line_len_out, /*delim=*/'\n');
+}
+
+#endif /* __API_IO__ */