On Mon, Jun 22, 2020 at 10:04:18AM -0700, Nick Desaulniers wrote:

On Fri, Jun 19, 2020 at 8:30 PM Kees Cook [off-list ref] wrote:

quoted

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

Fixes: 58619b14d106 ("b43: move under broadcom vendor directory")
Signed-off-by: Kees Cook <redacted>

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

quoted

---
 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