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, 117 insertions, 0 deletions

diff --git a/lib/kunit/user_alloc.c b/lib/kunit/user_alloc.c
new file mode 100644
index 000000000..b8cac765e
--- /dev/null
+++ b/lib/kunit/user_alloc.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit userspace memory allocation resource management.
+ */
+#include <kunit/resource.h>
+#include <kunit/test.h>
+#include <linux/kthread.h>
+#include <linux/mm.h>
+
+struct kunit_vm_mmap_resource {
+	unsigned long addr;
+	size_t size;
+};
+
+/* vm_mmap() arguments */
+struct kunit_vm_mmap_params {
+	struct file *file;
+	unsigned long addr;
+	unsigned long len;
+	unsigned long prot;
+	unsigned long flag;
+	unsigned long offset;
+};
+
+int kunit_attach_mm(void)
+{
+	struct mm_struct *mm;
+
+	if (current->mm)
+		return 0;
+
+	/* arch_pick_mmap_layout() is only sane with MMU systems. */
+	if (!IS_ENABLED(CONFIG_MMU))
+		return -EINVAL;
+
+	mm = mm_alloc();
+	if (!mm)
+		return -ENOMEM;
+
+	/* Define the task size. */
+	mm->task_size = TASK_SIZE;
+
+	/* Make sure we can allocate new VMAs. */
+	arch_pick_mmap_layout(mm, &current->signal->rlim[RLIMIT_STACK]);
+
+	/* Attach the mm. It will be cleaned up when the process dies. */
+	kthread_use_mm(mm);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kunit_attach_mm);
+
+static int kunit_vm_mmap_init(struct kunit_resource *res, void *context)
+{
+	struct kunit_vm_mmap_params *p = context;
+	struct kunit_vm_mmap_resource vres;
+	int ret;
+
+	ret = kunit_attach_mm();
+	if (ret)
+		return ret;
+
+	vres.size = p->len;
+	vres.addr = vm_mmap(p->file, p->addr, p->len, p->prot, p->flag, p->offset);
+	if (!vres.addr)
+		return -ENOMEM;
+	res->data = kmemdup(&vres, sizeof(vres), GFP_KERNEL);
+	if (!res->data) {
+		vm_munmap(vres.addr, vres.size);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void kunit_vm_mmap_free(struct kunit_resource *res)
+{
+	struct kunit_vm_mmap_resource *vres = res->data;
+
+	/*
+	 * Since this is executed from the test monitoring process,
+	 * the test's mm has already been torn down. We don't need
+	 * to run vm_munmap(vres->addr, vres->size), only clean up
+	 * the vres.
+	 */
+
+	kfree(vres);
+	res->data = NULL;
+}
+
+unsigned long kunit_vm_mmap(struct kunit *test, struct file *file,
+			    unsigned long addr, unsigned long len,
+			    unsigned long prot, unsigned long flag,
+			    unsigned long offset)
+{
+	struct kunit_vm_mmap_params params = {
+		.file = file,
+		.addr = addr,
+		.len = len,
+		.prot = prot,
+		.flag = flag,
+		.offset = offset,
+	};
+	struct kunit_vm_mmap_resource *vres;
+
+	vres = kunit_alloc_resource(test,
+				    kunit_vm_mmap_init,
+				    kunit_vm_mmap_free,
+				    GFP_KERNEL,
+				    &params);
+	if (vres)
+		return vres->addr;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kunit_vm_mmap);
+
+MODULE_IMPORT_NS("EXPORTED_FOR_KUNIT_TESTING");