On Sun, Jun 6, 2021 at 12:13 AM Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > On Sun, Jun 06, 2021 at 12:00:21AM -0700, Wenli Looi wrote: > > Uninitialized struct with invalid pointer causes BUG and prevents access > > point from working. Access point works once I apply this patch. > > > > https://forum.armbian.com/topic/14727-wifi-ap-kernel-bug-in-kernel-5444/ > > has more details. > > > > Signed-off-by: Wenli Looi <wlooi@xxxxxxxxxxx> > > --- > > drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c > > index 2fb80b6eb..7308e1185 100644 > > --- a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c > > +++ b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c > > @@ -2384,7 +2384,7 @@ void rtw_cfg80211_indicate_sta_assoc(struct adapter *padapter, u8 *pmgmt_frame, > > DBG_871X(FUNC_ADPT_FMT"\n", FUNC_ADPT_ARG(padapter)); > > > > { > > - struct station_info sinfo; > > + struct station_info sinfo = {}; > > What caused this bug to show up? Did it happen from some other commit? > > Are you sure that all of the fields are being cleared properly here, > what about any "holes" in the structure? > > thanks, > greg k-h I believe this bug has been present since the driver was added to staging: https://github.com/torvalds/linux/commit/554c0a3abf216c991c5ebddcdb2c08689ecd290b It's probably not necessary to zero the entire struct, only sinfo->pertid, which causes problems with the code here: https://github.com/torvalds/linux/blob/f5b6eb1e018203913dfefcf6fa988649ad11ad6e/net/wireless/nl80211.c#L5919 You can see the following proposed OpenWrt patch (700-wifi-8723bs-ap-bugfix.patch in https://github.com/openwrt/openwrt/pull/4053/files) which sets sinfo.pertid = 0; instead of zeroing the struct. Looking at similar code in a non-staging driver, we can see that the code there zeros the struct using kzalloc(): https://github.com/torvalds/linux/blob/f5b6eb1e018203913dfefcf6fa988649ad11ad6e/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c#L6064 Do you think kzalloc() would be preferable? Sorry, I'm not familiar with "holes" in the struct.
