linux-kernel - [PATCH 03/10] b43: Remove uninitialized

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Message-Id: <20200603233203.1695403-4-keescook@chromium.org>
Date:   Wed,  3 Jun 2020 16:31:56 -0700
From:   Kees Cook <keescook@...omium.org>
To:     linux-kernel@...r.kernel.org
Cc:     Kees Cook <keescook@...omium.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Joe Perches <joe@...ches.com>,
        Andy Whitcroft <apw@...onical.com>, x86@...nel.org,
        drbd-dev@...ts.linbit.com, linux-block@...r.kernel.org,
        b43-dev@...ts.infradead.org, netdev@...r.kernel.org,
        linux-wireless@...r.kernel.org, linux-ide@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-spi@...r.kernel.org,
        linux-mm@...ck.org, clang-built-linux@...glegroups.com
Subject: [PATCH 03/10] b43: Remove uninitialized_var() usage

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,
and make the (unreachable!) code do a conditional test.

[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/

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 drivers/net/wireless/broadcom/b43/phy_n.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/broadcom/b43/phy_n.c b/drivers/net/wireless/broadcom/b43/phy_n.c
index d3c001fa8eb4..88cdcea10d61 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)
@@ -4256,9 +4256,13 @@ static void b43_nphy_tx_gain_table_upload(struct b43_wldev *dev)
 			pga_gain = (table[i] >> 24) & 0xf;
 			pad_gain = (table[i] >> 19) & 0x1f;
 			if (b43_current_band(dev->wl) == NL80211_BAND_2GHZ)
-				rfpwr_offset = rf_pwr_offset_table[pad_gain];
+				rfpwr_offset = rf_pwr_offset_table
+						? rf_pwr_offset_table[pad_gain]
+						: 0;
 			else
-				rfpwr_offset = rf_pwr_offset_table[pga_gain];
+				rfpwr_offset = rf_pwr_offset_table
+						? rf_pwr_offset_table[pga_gain]
+						: 0;
 		} else {
 			pga_gain = (table[i] >> 24) & 0xF;
 			if (b43_current_band(dev->wl) == NL80211_BAND_2GHZ)
-- 
2.25.1