CVE-2024-35811

In the Linux kernel, the following vulnerability has been resolved:

wifi: brcmfmac: Fix use-after-free bug in brcmfcfg80211detach

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:

->brcmfusbprobe ->brcmfusbprobecb ->brcmfattach ->brcmfbusstarted ->brcmfcfg80211attach ->wlinitpriv ->brcmfinitescan ->INITWORK(&cfg->escantimeoutwork, brcmfcfg80211escantimeout_worker);

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

brcmfusbdisconnect ->brcmfusbdisconnectcb ->brcmfdetach ->brcmfcfg80211detach ->kfree(cfg);

While the timeout woker may still be running. This will cause a use-after-free bug on cfg in brcmfcfg80211escantimeoutworker.

Fix it by deleting the timer and canceling the worker in brcmfcfg80211detach.

[arend.vanspriel@broadcom.com: keep timer delete as is and cancel work just before free]