2023-11-04 05:49:31

by Zheng Wang

Subject: [PATCH] wifi: cfg80211: Fix use-after-free bug in brcmf_cfg80211_detach

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 <[email protected]>
Cc: [email protected]
---
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

2023-11-04 16:29:55

by Johannes Berg

Subject: Re: [PATCH] wifi: cfg80211: Fix use-after-free bug in brcmf_cfg80211_detach

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