Re: [PATCH] wifi: nl80211: fix bounds checker error in nl80211_parse_sched_scan

[Kees Cook <kees@kernel.org>]

On Mon, Oct 28, 2024 at 04:54:43PM -0600, Gustavo A. R. Silva wrote:
> 
> 
> On 28/10/24 16:18, Aleksei Vetrov via B4 Relay wrote:
> > From: Aleksei Vetrov <vvvvvv@google.com>
> > 
> > The channels array in the cfg80211_scan_request has a __counted_by
> > attribute attached to it, which points to the n_channels variable. This
> > attribute is used in bounds checking, and if it is not set before the
> > array is filled, then the bounds sanitizer will issue a warning or a
> > kernel panic if CONFIG_UBSAN_TRAP is set.
> > 
> > This patch sets the size of allocated memory as the initial value for
> > n_channels. It is updated with the actual number of added elements after
> > the array is filled.
> > 
> 
> This should include the following tag (and probably CC stable):
> 
> Fixes: aa4ec06c455d ("wifi: cfg80211: use __counted_by where appropriate")

Agreed.

Reviewed-by: Kees Cook <kees@kernel.org>

-Kees

> 
> Thanks
> --
> Gustavo
> 
> > Signed-off-by: Aleksei Vetrov <vvvvvv@google.com>
> > ---
> >   net/wireless/nl80211.c | 1 +
> >   1 file changed, 1 insertion(+)
> > 
> > diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
> > index d7d099f7118ab5d5c745905abdea85d246c2b7b2..9b1b9dc5a7eb2a864da7b0212bc6a156b7757a9d 100644
> > --- a/net/wireless/nl80211.c
> > +++ b/net/wireless/nl80211.c
> > @@ -9776,6 +9776,7 @@ nl80211_parse_sched_scan(struct wiphy *wiphy, struct wireless_dev *wdev,
> >   	request = kzalloc(size, GFP_KERNEL);
> >   	if (!request)
> >   		return ERR_PTR(-ENOMEM);
> > +	request->n_channels = n_channels;
> >   	if (n_ssids)
> >   		request->ssids = (void *)request +
> > 
> > ---
> > base-commit: 81983758430957d9a5cb3333fe324fd70cf63e7e
> > change-id: 20241028-nl80211_parse_sched_scan-bounds-checker-fix-c5842f41b863
> > 
> > Best regards,
> 

-- 
Kees Cook