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, 76 insertions, 0 deletions

diff --git a/fs/ecryptfs/dentry.c b/fs/ecryptfs/dentry.c
new file mode 100644
index 000000000..6648a924e
--- /dev/null
+++ b/fs/ecryptfs/dentry.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * eCryptfs: Linux filesystem encryption layer
+ *
+ * Copyright (C) 1997-2003 Erez Zadok
+ * Copyright (C) 2001-2003 Stony Brook University
+ * Copyright (C) 2004-2006 International Business Machines Corp.
+ *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
+ */
+
+#include <linux/dcache.h>
+#include <linux/namei.h>
+#include <linux/mount.h>
+#include <linux/fs_stack.h>
+#include <linux/slab.h>
+#include "ecryptfs_kernel.h"
+
+/**
+ * ecryptfs_d_revalidate - revalidate an ecryptfs dentry
+ * @dir: inode of expected parent
+ * @name: expected name
+ * @dentry: dentry to revalidate
+ * @flags: lookup flags
+ *
+ * Called when the VFS needs to revalidate a dentry. This
+ * is called whenever a name lookup finds a dentry in the
+ * dcache. Most filesystems leave this as NULL, because all their
+ * dentries in the dcache are valid.
+ *
+ * Returns 1 if valid, 0 otherwise.
+ *
+ */
+static int ecryptfs_d_revalidate(struct inode *dir, const struct qstr *name,
+				 struct dentry *dentry, unsigned int flags)
+{
+	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
+	int rc = 1;
+
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+
+	if (lower_dentry->d_flags & DCACHE_OP_REVALIDATE) {
+		struct inode *lower_dir = ecryptfs_inode_to_lower(dir);
+		struct name_snapshot n;
+
+		take_dentry_name_snapshot(&n, lower_dentry);
+		rc = lower_dentry->d_op->d_revalidate(lower_dir, &n.name,
+						      lower_dentry, flags);
+		release_dentry_name_snapshot(&n);
+	}
+
+	if (d_really_is_positive(dentry)) {
+		struct inode *inode = d_inode(dentry);
+
+		fsstack_copy_attr_all(inode, ecryptfs_inode_to_lower(inode));
+		if (!inode->i_nlink)
+			return 0;
+	}
+	return rc;
+}
+
+/**
+ * ecryptfs_d_release
+ * @dentry: The ecryptfs dentry
+ *
+ * Called when a dentry is really deallocated.
+ */
+static void ecryptfs_d_release(struct dentry *dentry)
+{
+	dput(dentry->d_fsdata);
+}
+
+const struct dentry_operations ecryptfs_dops = {
+	.d_revalidate = ecryptfs_d_revalidate,
+	.d_release = ecryptfs_d_release,
+};