[v2,09/16] clk: spear: Remove uninitialized_var() usage
diff mbox series

Message ID 20200620033007.1444705-10-keescook@chromium.org
State New
Headers show
Series
  • Remove uninitialized_var() macro
Related show

Commit Message

Kees Cook June 20, 2020, 3:30 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], initialize "i" to zero. The compiler
warning was not a false positive, since clk_pll_set_rate()'s call to
clk_pll_round_rate_index() will always fail (since "prate" is NULL), so
"i" was never being initialized.

[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: 7d4998f71b29 ("clk: SPEAr: Vco-pll: Fix compilation warning")
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/clk/spear/clk-vco-pll.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Stephen Boyd June 22, 2020, 9:03 a.m. UTC | #1
Quoting Kees Cook (2020-06-19 20:30:00)
> 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], initialize "i" to zero. The compiler
> warning was not a false positive, since clk_pll_set_rate()'s call to
> clk_pll_round_rate_index() will always fail (since "prate" is NULL), so
> "i" was never being initialized.
> 
> [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: 7d4998f71b29 ("clk: SPEAr: Vco-pll: Fix compilation warning")
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---

Acked-by: Stephen Boyd <sboyd@kernel.org>

Patch
diff mbox series

diff --git a/drivers/clk/spear/clk-vco-pll.c b/drivers/clk/spear/clk-vco-pll.c
index c08dec30bfa6..fed194169666 100644
--- a/drivers/clk/spear/clk-vco-pll.c
+++ b/drivers/clk/spear/clk-vco-pll.c
@@ -147,7 +147,7 @@  static int clk_pll_set_rate(struct clk_hw *hw, unsigned long drate,
 	struct clk_pll *pll = to_clk_pll(hw);
 	struct pll_rate_tbl *rtbl = pll->vco->rtbl;
 	unsigned long flags = 0, val;
-	int uninitialized_var(i);
+	int i = 0;
 
 	clk_pll_round_rate_index(hw, drate, NULL, &i);