From: https://gist.githubusercontent.com/joanbm/438536d70b6b55f69d3974d936aea1f7/raw/d2f4f1c6ce15046f7ce2906415a93cdf40a8f564/broadcom-wl-fix-linux-6.15.patch
Date: Sun, 23 Feb 2025 14:29:21 +0000
Subject: [PATCH] Tentative patch for broadcom-wl 6.30.223.271 driver for Linux
 6.15-rc1

Due to the fact that the driver is unmaintained, and can't be adapted
to the current Linux kernel security standards (e.g. IBT), as it has a
proprietary blob; and this is likely to be an ever-growing security
risk, I have added a warning when the module is loaded.
Use at your own risk; no warranty of any kind is provided.
See also the objtool changes on the Makefile below.

The changes to replace EXTRA_CFLAGS and EXTRA_LDFLAGS with ccflags-y
and ldflags-y are rel. commit "kbuild: remove EXTRA_*FLAGS support"
(Masahiro Yamada, 6 Feb 2025), according to which they have been
deprecated since 2007, so no need to add any fallback for old kernels.

NB: If the package build also contains references to EXTRA_*FLAGS
(e.g. Arch Linux's broadcom-wl-dkms PKGBUILD), replace those as well!
--- a/Makefile
+++ b/Makefile
@@ -117,15 +117,15 @@ GCCVERSION := $(subst $(space),$(empty),$(GCCVERSION))
 GCCVERSION := $(shell expr `echo $(GCCVERSION)` | cut -b1-3)
 GE_49 := $(shell expr `echo $(GCCVERSION)` \>= 490)
 
-EXTRA_CFLAGS :=
+ccflags-y :=
 
 ifeq ($(APIFINAL),CFG80211)
-  EXTRA_CFLAGS += -DUSE_CFG80211
+  ccflags-y += -DUSE_CFG80211
   $(info Using CFG80211 API)
 endif
 
 ifeq ($(APIFINAL),WEXT)
-  EXTRA_CFLAGS += -DUSE_IW
+  ccflags-y += -DUSE_IW
   $(info Using Wireless Extension API)
 endif
 
@@ -137,15 +137,15 @@ wl-objs            += src/wl/sys/wl_linux.o
 wl-objs            += src/wl/sys/wl_iw.o
 wl-objs            += src/wl/sys/wl_cfg80211_hybrid.o
 
-EXTRA_CFLAGS       += -I$(src)/src/include -I$(src)/src/common/include
-EXTRA_CFLAGS       += -I$(src)/src/wl/sys -I$(src)/src/wl/phy -I$(src)/src/wl/ppr/include
-EXTRA_CFLAGS       += -I$(src)/src/shared/bcmwifi/include
-#EXTRA_CFLAGS       += -DBCMDBG_ASSERT -DBCMDBG_ERR
+ccflags-y          += -I$(src)/src/include -I$(src)/src/common/include
+ccflags-y          += -I$(src)/src/wl/sys -I$(src)/src/wl/phy -I$(src)/src/wl/ppr/include
+ccflags-y          += -I$(src)/src/shared/bcmwifi/include
+#ccflags-y          += -DBCMDBG_ASSERT -DBCMDBG_ERR
 ifeq "$(GE_49)" "1"
-EXTRA_CFLAGS       += -Wno-date-time
+ccflags-y          += -Wno-date-time
 endif
 
-EXTRA_LDFLAGS      := $(src)/lib/wlc_hybrid.o_shipped
+ldflags-y          := $(src)/lib/wlc_hybrid.o_shipped
 
 KBASE              ?= /lib/modules/`uname -r`
 KBUILD_DIR         ?= $(KBASE)/build
@@ -155,6 +155,21 @@ MDEST_DIR          ?= $(KBASE)/kernel/drivers/net/wireless
 CROSS_TOOLS        = /path/to/tools
 CROSS_KBUILD_DIR   = /path/to/kernel/tree
 
+# Rel. commit "objtool: Always fail on fatal errors" (Josh Poimboeuf, 31 Mar 2025)
+# This is a *ugly* hack to disable objtool during the final processing of wl.o.
+# Since is embeds the proprietary blob (wlc_hybrid.o_shipped), objtool can't
+# process it, as it does not follow the requirements of current kernels,
+# including support for critical security features. As of Linux v6.15+, it causes
+# a build error. Disable it, at your own risk. Note the MIT license applies:
+# THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+wl.o: override objtool-enabled =
+
 all:
 	KBUILD_NOPEDANTIC=1 make -C $(KBUILD_DIR) M=`pwd`
 
--- a/src/wl/sys/wl_linux.c
+++ b/src/wl/sys/wl_linux.c
@@ -168,6 +168,8 @@ static int wl_set_radio_block(void *data, bool blocked);
 static void wl_report_radio_state(wl_info_t *wl);
 #endif
 
+// Rel. commit "modpost: require a MODULE_DESCRIPTION()" (Jeff Johnson, 11 Mar 2025)
+MODULE_DESCRIPTION("Broadcom-wl wireless driver [unmaintained, out-of-tree]");
 MODULE_LICENSE("MIXED/Proprietary");
 
 static struct pci_device_id wl_id_table[] =
@@ -914,6 +916,10 @@ static struct pci_driver wl_pci_driver __refdata = {
 static int __init
 wl_module_init(void)
 {
+	printk(KERN_WARNING "You are using the broadcom-wl driver, which is not "
+		"maintained and is incompatible with Linux kernel security mitigations. "
+		"It is heavily recommended to replace the hardware and remove the driver. "
+		"Proceed at your own risk!");
 	int error = -ENODEV;
 
 #ifdef BCMDBG
@@ -2457,7 +2463,12 @@ wl_del_timer(wl_info_t *wl, wl_timer_t *t)
 	ASSERT(t);
 	if (t->set) {
 		t->set = FALSE;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 15, 0)
+		// Rel. commit "treewide: Switch/rename to timer_delete[_sync]()" (Thomas Gleixner, 5 Apr 2025)
+		if (!timer_delete(&t->timer)) {
+#else
 		if (!del_timer(&t->timer)) {
+#endif
 #ifdef BCMDBG
 			WL_INFORM(("wl%d: Failed to delete timer %s\n", wl->unit, t->name));
 #endif
-- 
2.49.0