On 13-3-2017 10:33, Arend Van Spriel wrote: > On 6-3-2017 15:50, Daniel J Blueman wrote: >> On 6 March 2017 at 21:00, Arend Van Spriel <arend.vanspriel@xxxxxxxxxxxx> wrote: >>> + linux-wireless >>> >>> On 6-3-2017 8:14, Daniel J Blueman wrote: >>>> KASAN reported 'struct wireless_dev wdev' was read after being freed. >>>> Fix by freeing after the access. >>> >>> I would rather like to see the KASAN report, because something is off >>> here. This function is called with wdev as a parameter so how can it be >>> accessed after free here? brcmf_remove_interface() does not free the >>> wdev nor the brcmf_cfg80211_vif instance which contains the wdev. >>> >>> Regards, >>> Arend >>> >>>> Signed-off-by: Daniel J Blueman <daniel@xxxxxxxxx> >>>> >>>> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c >>>> b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c >>>> index de19c7c..aa0f470 100644 >>>> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c >>>> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c >>>> @@ -2288,12 +2288,13 @@ int brcmf_p2p_del_vif(struct wiphy *wiphy, >>>> struct wireless_dev *wdev) >>>> else >>>> err = 0; >>>> } >>>> - brcmf_remove_interface(vif->ifp, true); >>>> >>>> - brcmf_cfg80211_arm_vif_event(cfg, NULL); >>>> if (vif->wdev.iftype != NL80211_IFTYPE_P2P_DEVICE) >>>> p2p->bss_idx[P2PAPI_BSSCFG_CONNECTION].vif = NULL; >>>> >>>> + brcmf_remove_interface(vif->ifp, true); >>>> + brcmf_cfg80211_arm_vif_event(cfg, NULL); >>>> + >>>> return err; >>>> } >> >> Sure, https://quora.org/kernel/brcmfmac/dmesg.txt > > So this dmesg looks to be about a separate issue during resume, which > you sent an email about earlier [1] which is about using wiphy struct > after free. However, back to this I further checked the code and it > seems the vif is indeed freed through the netdev destructor callback > upon calling brcmf_remove_inteface(). However, I would prefer to store > vif->wdev.iftype in a local variable and avoid changing the order of the > calls in the code. Forgot to mention some things about the commit message. Please drop the the kernel version from the subject. You should create the patch against the wireless-drivers tree and indicate the patch is for 4.11, ie. "[PATCH for-4.11] brcmfmac: fix use-after-free of wireless_dev instance". Also add as much useful information in the commit message as possible like the proper KASAN report or at least mention that brcmf_remove_interface() does an unregister_netdev() which results in freeing the wireless_dev through netdev destructor callback. Regards, Arend > Regards, > Arend > > [1] http://marc.info/?l=linux-netdev&m=148878437808750&w=2 > >> vmlinux, cfg80211.o, brcmfmac.o and config are in the same path; this >> is against v4.9.13 stock. >
