Re: [PATCH] macb: Don't unregister clks unconditionally

From: David Miller
Date: Sun Jan 05 2020 - 18:11:28 EST

From: Stephen Boyd <sboyd@xxxxxxxxxx>
Date: Fri, 3 Jan 2020 16:19:21 -0800

> The only clk init function in this driver that register a clk is
> fu540_c000_clk_init(), and thus we need to unregister the clk when this
> driver is removed on that platform. Other init functions, for example
> macb_clk_init(), don't register clks and therefore we shouldn't
> unregister the clks when this driver is removed. Convert this
> registration path to devm so it gets auto-unregistered when this driver
> is removed and drop the clk_unregister() calls in driver remove (and
> error paths) so that we don't erroneously remove a clk from the system
> that isn't registered by this driver.
> Otherwise we get strange crashes with a use-after-free when the
> devm_clk_get() call in macb_clk_init() calls clk_put() on a clk pointer
> that has become invalid because it is freed in clk_unregister().
> Cc: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx>
> Cc: Yash Shah <yash.shah@xxxxxxxxxx>
> Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> Fixes: c218ad559020 ("macb: Add support for SiFive FU540-C000")
> Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxx>

Applied and queued up for -stable, thanks.