Re: [PATCH] mac80211: initialize variable have_higher_than_11mbit

[Tom Rix]

On 12/23/21 12:30 PM, Nick Desaulniers wrote:
> On Thu, Dec 23, 2021 at 8:29 AM <trix@xxxxxxxxxx> wrote:
> > From: Tom Rix <trix@xxxxxxxxxx>
> >
> > Clang static analysis reports this warnings
> >
> > mlme.c:5332:7: warning: Branch condition evaluates to a
> >    garbage value
> >      have_higher_than_11mbit)
> >      ^~~~~~~~~~~~~~~~~~~~~~~
> >
> > have_higher_than_11mbit is only set to true some of the time in
> > ieee80211_get_rates() but is checked all of the time.  So
> > have_higher_than_11mbit needs to be initialized to false.
> LGTM. There's only one caller of ieee80211_get_rates() today; if there
> were others, they could make a similar mistake in the future. An
> alternate approach: ieee80211_get_rates() could unconditionally write
> false before the loop that could later write true. Then call sites
> don't need to worry about this conditional assignment. Perhaps that
> would be preferable? If not:

The have_higher_than_11mbit variable had previously be initialized to false.

The commit 5d6a1b069b7f moved the variable without initializing.

Tom

> Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
>
> > Fixes: 5d6a1b069b7f ("mac80211: set basic rates earlier")
> > Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
> > ---
> >   net/mac80211/mlme.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
> > index 51f55c4ee3c6e..766cbbc9c3a72 100644
> > --- a/net/mac80211/mlme.c
> > +++ b/net/mac80211/mlme.c
> > @@ -5279,7 +5279,7 @@ static int ieee80211_prep_connection(struct ieee80211_sub_if_data *sdata,
> >           */
> >          if (new_sta) {
> >                  u32 rates = 0, basic_rates = 0;
> > -               bool have_higher_than_11mbit;
> > +               bool have_higher_than_11mbit = false;
> >                  int min_rate = INT_MAX, min_rate_index = -1;
> >                  const struct cfg80211_bss_ies *ies;
> >                  int shift = ieee80211_vif_get_shift(&sdata->vif);
> > --
> > 2.26.3