On Sunday, June 6, 2021 10:09:39 AM CEST Wenli Looi wrote: > On Sun, Jun 6, 2021 at 1:00 AM Fabio M. De Francesco > > <fmdefrancesco@xxxxxxxxx> wrote: > > On Sunday, June 6, 2021 9:51:35 AM CEST Wenli Looi wrote: > > > 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 [CUT] > > > > > > Do you think kzalloc() would be preferable? > > > > You cannot use kzalloc there: 'sinfo' is instantiated automatically on the > > stack. The example you took had a pointer to the struct. > > The stack variable could be replaced with code like: > > struct station_info *sinfo;if (!sinfo) > Why that "if (!sinfo" before kzalloc? > > sinfo = kzalloc(sizeof(*sinfo), GFP_KERNEL); > ... > cfg80211_new_sta(..., sinfo, ...); > kfree(sinfo); > > which is what the linked code basically does. I'm not sure if this is preferred? > I don't know that code, but I think that: (1) It is generally preferred that big structures should be allocated dinamically: kernel stack is a scarce resource. (2) Passing address of variables from the stack to other functions is generally a good source of troubles. I think you are closer to the proper solution. Fabio > > > > > > Sorry, I'm not familiar with "holes" in the struct.
