In brcm80211 driver,it starts with the following invoking chain
to start init a timeout worker:

->brcmf_usb_probe
  ->brcmf_usb_probe_cb
    ->brcmf_attach
      ->brcmf_bus_started
        ->brcmf_cfg80211_attach
          ->wl_init_priv
            ->brcmf_init_escan
              ->INIT_WORK(&cfg->escan_timeout_work,
		  brcmf_cfg80211_escan_timeout_worker);

If we disconnect the USB by hotplug, it will call
brcmf_usb_disconnect to make cleanup. The invoking chain is :

brcmf_usb_disconnect
  ->brcmf_usb_disconnect_cb
    ->brcmf_detach
      ->brcmf_cfg80211_detach
        ->kfree(cfg);

While the timeout woker may still be running. This will cause
a use-after-free bug on cfg in brcmf_cfg80211_escan_timeout_worker.

Fix it by deleting the timer and canceling the worker in
brcmf_cfg80211_detach.

Fixes: e756af5b30b0 ("brcmfmac: add e-scan support.")
Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
Cc: stable@vger.kernel.org
---
 drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
index 667462369a32..0224e377eb6e 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
@@ -8431,6 +8431,9 @@ void brcmf_cfg80211_detach(struct brcmf_cfg80211_info *cfg)
 	if (!cfg)
 		return;
 
+	if (timer_pending(&cfg->escan_timeout))
+		del_timer_sync(&cfg->escan_timeout);
+	cancel_delayed_work_sync(&cfg->escan_timeout_work);
 	brcmf_pno_detach(cfg);
 	brcmf_btcoex_detach(cfg);
 	wiphy_unregister(cfg->wiphy);
-- 
2.25.1

On Sat, 2023-11-04 at 13:47 +0800, Zheng Wang wrote:
> 
>  drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 3 +++
> 

Nothing to do with cfg80211, please fix the subject.

johannes

Hi Zheng,

kernel test robot noticed the following build errors:

[auto build test ERROR on wireless-next/main]
[also build test ERROR on wireless/main linus/master v6.6 next-20231103]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Zheng-Wang/wifi-cfg80211-Fix-use-after-free-bug-in-brcmf_cfg80211_detach/20231104-135107
base:   https://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless-next.git main
patch link:    https://lore.kernel.org/r/20231104054709.716585-1-zyytlz.wz%40163.com
patch subject: [PATCH] wifi: cfg80211: Fix use-after-free bug in brcmf_cfg80211_detach
config: arc-randconfig-002-20231104 (https://download.01.org/0day-ci/archive/20231104/202311041735.pCIzwiLF-lkp@intel.com/config)
compiler: arceb-elf-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231104/202311041735.pCIzwiLF-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202311041735.pCIzwiLF-lkp@intel.com/

All errors (new ones prefixed by >>):

   drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c: In function 'brcmf_cfg80211_detach':
>> drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c:8436:34: error: passing argument 1 of 'cancel_delayed_work_sync' from incompatible pointer type [-Werror=incompatible-pointer-types]
    8436 |         cancel_delayed_work_sync(&cfg->escan_timeout_work);
         |                                  ^~~~~~~~~~~~~~~~~~~~~~~~
         |                                  |
         |                                  struct work_struct *
   In file included from include/linux/mm_types.h:19,
                    from include/linux/mmzone.h:22,
                    from include/linux/gfp.h:7,
                    from include/linux/xarray.h:15,
                    from include/linux/list_lru.h:14,
                    from include/linux/fs.h:13,
                    from include/linux/highmem.h:5,
                    from include/linux/bvec.h:10,
                    from include/linux/skbuff.h:17,
                    from include/linux/if_ether.h:19,
                    from include/linux/etherdevice.h:20,
                    from drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c:9:
   include/linux/workqueue.h:511:59: note: expected 'struct delayed_work *' but argument is of type 'struct work_struct *'
     511 | extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
         |                                      ~~~~~~~~~~~~~~~~~~~~~^~~~~
   cc1: some warnings being treated as errors


vim +/cancel_delayed_work_sync +8436 drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c

  8428	
  8429	void brcmf_cfg80211_detach(struct brcmf_cfg80211_info *cfg)
  8430	{
  8431		if (!cfg)
  8432			return;
  8433	
  8434		if (timer_pending(&cfg->escan_timeout))
  8435			del_timer_sync(&cfg->escan_timeout);
> 8436		cancel_delayed_work_sync(&cfg->escan_timeout_work);

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki