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From: Arend van Spriel <arend.vanspriel@broadcom.com>
To: Kalle Valo <kvalo@kernel.org>
Cc: linux-wireless@vger.kernel.org,
	Zheng Wang <zyytlz.wz@163.com>,
	stable@vger.kernel.org,
	Arend van Spriel <arend.vanspriel@broadcom.com>
Subject: [PATCH V6] wifi: brcmfmac: Fix use-after-free bug in brcmf_cfg80211_detach
Date: Sun,  7 Jan 2024 08:25:04 +0100
Message-Id: <20240107072504.392713-1-arend.vanspriel@broadcom.com>
Precedence: bulk
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From: Zheng Wang <zyytlz.wz@163.com>

This is the candidate patch of CVE-2023-47233 :
https://nvd.nist.gov/vuln/detail/CVE-2023-47233

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
[arend.vanspriel@broadcom.com: keep timer delete as is and cancel work just before free]
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
---
 drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
index 133c5ea6429c..52df03243c9f 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
@@ -1179,8 +1179,7 @@ s32 brcmf_notify_escan_complete(struct brcmf_cfg80211_info *cfg,
 	scan_request = cfg->scan_request;
 	cfg->scan_request = NULL;
 
-	if (timer_pending(&cfg->escan_timeout))
-		del_timer_sync(&cfg->escan_timeout);
+	timer_delete_sync(&cfg->escan_timeout);
 
 	if (fw_abort) {
 		/* Do a scan abort to stop the driver's scan engine */
@@ -8435,6 +8434,7 @@ void brcmf_cfg80211_detach(struct brcmf_cfg80211_info *cfg)
 	brcmf_btcoex_detach(cfg);
 	wiphy_unregister(cfg->wiphy);
 	wl_deinit_priv(cfg);
+	cancel_work_sync(&cfg->escan_timeout_work);
 	brcmf_free_wiphy(cfg->wiphy);
 	kfree(cfg);
 }

base-commit: 3aca362a4c1411ec11ff04f81b6cdf2359fee962
-- 
2.32.0


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