[v2,04/16] b43: Remove uninitialized_var() usage
diff mbox series

Message ID 20200620033007.1444705-5-keescook@chromium.org
State New
Headers show
Series
  • Remove uninitialized_var() macro
Related show

Commit Message

Kees Cook June 20, 2020, 3:29 a.m. UTC
Using uninitialized_var() is dangerous as it papers over real bugs[1]
(or can in the future), and suppresses unrelated compiler warnings (e.g.
"unused variable"). If the compiler thinks it is uninitialized, either
simply initialize the variable or make compiler changes. As a precursor
to removing[2] this[3] macro[4], just initialize this variable to NULL.
No later NULL deref is possible due to the early returns outside of the
(phy->rev >= 7 && phy->rev < 19) case, which explicitly tests for NULL.

[1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/

Fixes: 58619b14d106 ("b43: move under broadcom vendor directory")
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/net/wireless/broadcom/b43/phy_n.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Nick Desaulniers June 22, 2020, 5:04 p.m. UTC | #1
On Fri, Jun 19, 2020 at 8:30 PM Kees Cook <keescook@chromium.org> wrote:
>
> Using uninitialized_var() is dangerous as it papers over real bugs[1]
> (or can in the future), and suppresses unrelated compiler warnings (e.g.
> "unused variable"). If the compiler thinks it is uninitialized, either
> simply initialize the variable or make compiler changes. As a precursor
> to removing[2] this[3] macro[4], just initialize this variable to NULL.
> No later NULL deref is possible due to the early returns outside of the
> (phy->rev >= 7 && phy->rev < 19) case, which explicitly tests for NULL.
>
> [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
> [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
> [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
> [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
>
> Fixes: 58619b14d106 ("b43: move under broadcom vendor directory")
> Signed-off-by: Kees Cook <keescook@chromium.org>

I see three total uses of uninitialized_var() in this file, do we want
to eliminate all of them?

> ---
>  drivers/net/wireless/broadcom/b43/phy_n.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/broadcom/b43/phy_n.c b/drivers/net/wireless/broadcom/b43/phy_n.c
> index c33b4235839d..46db91846007 100644
> --- a/drivers/net/wireless/broadcom/b43/phy_n.c
> +++ b/drivers/net/wireless/broadcom/b43/phy_n.c
> @@ -4222,7 +4222,7 @@ static void b43_nphy_tx_gain_table_upload(struct b43_wldev *dev)
>         u32 rfpwr_offset;
>         u8 pga_gain, pad_gain;
>         int i;
> -       const s16 *uninitialized_var(rf_pwr_offset_table);
> +       const s16 *rf_pwr_offset_table = NULL;
>
>         table = b43_nphy_get_tx_gain_table(dev);
>         if (!table)
> --
Kees Cook June 22, 2020, 9:04 p.m. UTC | #2
On Mon, Jun 22, 2020 at 10:04:18AM -0700, Nick Desaulniers wrote:
> On Fri, Jun 19, 2020 at 8:30 PM Kees Cook <keescook@chromium.org> wrote:
> >
> > Using uninitialized_var() is dangerous as it papers over real bugs[1]
> > (or can in the future), and suppresses unrelated compiler warnings (e.g.
> > "unused variable"). If the compiler thinks it is uninitialized, either
> > simply initialize the variable or make compiler changes. As a precursor
> > to removing[2] this[3] macro[4], just initialize this variable to NULL.
> > No later NULL deref is possible due to the early returns outside of the
> > (phy->rev >= 7 && phy->rev < 19) case, which explicitly tests for NULL.
> >
> > [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
> > [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
> > [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
> > [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
> >
> > Fixes: 58619b14d106 ("b43: move under broadcom vendor directory")
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> 
> I see three total uses of uninitialized_var() in this file, do we want
> to eliminate all of them?

This is the only one that needed an explicit initialization -- all the
others are handled in the treewide patch. I *could* split it out here,
but I found it easier to keep the "no op" changes together in the
treewide patch.

-Kees

> 
> > ---
> >  drivers/net/wireless/broadcom/b43/phy_n.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/wireless/broadcom/b43/phy_n.c b/drivers/net/wireless/broadcom/b43/phy_n.c
> > index c33b4235839d..46db91846007 100644
> > --- a/drivers/net/wireless/broadcom/b43/phy_n.c
> > +++ b/drivers/net/wireless/broadcom/b43/phy_n.c
> > @@ -4222,7 +4222,7 @@ static void b43_nphy_tx_gain_table_upload(struct b43_wldev *dev)
> >         u32 rfpwr_offset;
> >         u8 pga_gain, pad_gain;
> >         int i;
> > -       const s16 *uninitialized_var(rf_pwr_offset_table);
> > +       const s16 *rf_pwr_offset_table = NULL;
> >
> >         table = b43_nphy_get_tx_gain_table(dev);
> >         if (!table)
> > --
> 
> -- 
> Thanks,
> ~Nick Desaulniers
Nick Desaulniers June 23, 2020, 6:29 p.m. UTC | #3
On Mon, Jun 22, 2020 at 2:04 PM Kees Cook <keescook@chromium.org> wrote:
>
> On Mon, Jun 22, 2020 at 10:04:18AM -0700, Nick Desaulniers wrote:
> > On Fri, Jun 19, 2020 at 8:30 PM Kees Cook <keescook@chromium.org> wrote:
> > >
> > > Using uninitialized_var() is dangerous as it papers over real bugs[1]
> > > (or can in the future), and suppresses unrelated compiler warnings (e.g.
> > > "unused variable"). If the compiler thinks it is uninitialized, either
> > > simply initialize the variable or make compiler changes. As a precursor
> > > to removing[2] this[3] macro[4], just initialize this variable to NULL.
> > > No later NULL deref is possible due to the early returns outside of the
> > > (phy->rev >= 7 && phy->rev < 19) case, which explicitly tests for NULL.
> > >
> > > [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
> > > [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
> > > [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
> > > [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
> > >
> > > Fixes: 58619b14d106 ("b43: move under broadcom vendor directory")
> > > Signed-off-by: Kees Cook <keescook@chromium.org>
> >
> > I see three total uses of uninitialized_var() in this file, do we want
> > to eliminate all of them?
>
> This is the only one that needed an explicit initialization -- all the
> others are handled in the treewide patch. I *could* split it out here,
> but I found it easier to keep the "no op" changes together in the
> treewide patch.

Ah, got it.
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

>
> -Kees
>
> >
> > > ---
> > >  drivers/net/wireless/broadcom/b43/phy_n.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/net/wireless/broadcom/b43/phy_n.c b/drivers/net/wireless/broadcom/b43/phy_n.c
> > > index c33b4235839d..46db91846007 100644
> > > --- a/drivers/net/wireless/broadcom/b43/phy_n.c
> > > +++ b/drivers/net/wireless/broadcom/b43/phy_n.c
> > > @@ -4222,7 +4222,7 @@ static void b43_nphy_tx_gain_table_upload(struct b43_wldev *dev)
> > >         u32 rfpwr_offset;
> > >         u8 pga_gain, pad_gain;
> > >         int i;
> > > -       const s16 *uninitialized_var(rf_pwr_offset_table);
> > > +       const s16 *rf_pwr_offset_table = NULL;
> > >
> > >         table = b43_nphy_get_tx_gain_table(dev);
> > >         if (!table)
> > > --
> >
> > --
> > Thanks,
> > ~Nick Desaulniers
>
> --
> Kees Cook
Kalle Valo July 15, 2020, 10:37 a.m. UTC | #4
Kees Cook <keescook@chromium.org> wrote:

> Using uninitialized_var() is dangerous as it papers over real bugs[1]
> (or can in the future), and suppresses unrelated compiler warnings (e.g.
> "unused variable"). If the compiler thinks it is uninitialized, either
> simply initialize the variable or make compiler changes. As a precursor
> to removing[2] this[3] macro[4], just initialize this variable to NULL.
> No later NULL deref is possible due to the early returns outside of the
> (phy->rev >= 7 && phy->rev < 19) case, which explicitly tests for NULL.
> 
> [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
> [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
> [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
> [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
> 
> Fixes: 58619b14d106 ("b43: move under broadcom vendor directory")
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

2 patches applied to wireless-drivers-next.git, thanks.

800e7a205a0f b43: Remove uninitialized_var() usage
f8279dad4e36 rtlwifi: rtl8192cu: Remove uninitialized_var() usage

Patch
diff mbox series

diff --git a/drivers/net/wireless/broadcom/b43/phy_n.c b/drivers/net/wireless/broadcom/b43/phy_n.c
index c33b4235839d..46db91846007 100644
--- a/drivers/net/wireless/broadcom/b43/phy_n.c
+++ b/drivers/net/wireless/broadcom/b43/phy_n.c
@@ -4222,7 +4222,7 @@  static void b43_nphy_tx_gain_table_upload(struct b43_wldev *dev)
 	u32 rfpwr_offset;
 	u8 pga_gain, pad_gain;
 	int i;
-	const s16 *uninitialized_var(rf_pwr_offset_table);
+	const s16 *rf_pwr_offset_table = NULL;
 
 	table = b43_nphy_get_tx_gain_table(dev);
 	if (!table)