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[PATCH] clk: sunxi: fix uninitialized access

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  [PATCH] clk: sunxi: fix uninitialized access Arnd Bergmann <arnd@arndb.de> - 2017-08-23 16:50 +0200
    Re: [PATCH] clk: sunxi: fix uninitialized access Maxime Ripard <maxime.ripard@free-electrons.com> - 2017-08-24 11:00 +0200

#1718430 — [PATCH] clk: sunxi: fix uninitialized access

gcc-8 reports an uninitialized variable access in a code path
that we would see with incorrect DTB input:

drivers/clk/sunxi/clk-sun8i-bus-gates.c: In function 'sun8i_h3_bus_gates_init':
drivers/clk/sunxi/clk-sun8i-bus-gates.c:85:27: error: 'clk_parent' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This works around by skipping invalid input and printing a warning
instead if it ever happens. The problem was apparently part of the
initiali driver submission, but older compilers don't notice it.

Fixes: ab6e23a4e388 ("clk: sunxi: Add H3 clocks support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/clk/sunxi/clk-sun8i-bus-gates.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/clk/sunxi/clk-sun8i-bus-gates.c b/drivers/clk/sunxi/clk-sun8i-bus-gates.c
index 63fdb790df29..bee305bdddbe 100644
--- a/drivers/clk/sunxi/clk-sun8i-bus-gates.c
+++ b/drivers/clk/sunxi/clk-sun8i-bus-gates.c
@@ -78,6 +78,10 @@ static void __init sun8i_h3_bus_gates_init(struct device_node *node)
 			clk_parent = APB1;
 		else if (index >= 96 && index <= 127)
 			clk_parent = APB2;
+		else {
+			WARN_ON(true);
+			continue;
+		}
 
 		clk_reg = reg + 4 * (index / 32);
 		clk_bit = index % 32;
-- 
2.9.0

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#1719027

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On Wed, Aug 23, 2017 at 04:39:27PM +0200, Arnd Bergmann wrote:
> gcc-8 reports an uninitialized variable access in a code path
> that we would see with incorrect DTB input:
> 
> drivers/clk/sunxi/clk-sun8i-bus-gates.c: In function 'sun8i_h3_bus_gates_init':
> drivers/clk/sunxi/clk-sun8i-bus-gates.c:85:27: error: 'clk_parent' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> 
> This works around by skipping invalid input and printing a warning
> instead if it ever happens. The problem was apparently part of the
> initiali driver submission, but older compilers don't notice it.
> 
> Fixes: ab6e23a4e388 ("clk: sunxi: Add H3 clocks support")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

That's weird it stayed for that long without any compiler noticing.

Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>

Mike, Stephen, can you pick it up as a fix? We don't have anything
else coming your way.

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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