Commit d89091a4 authored Jan 03, 2020 by Stephen Boyd Committed by David S. Miller Jan 05, 2020

macb: Don't unregister clks unconditionally



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@microchip.com>
Cc: Yash Shah <yash.shah@sifive.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Fixes: c218ad55 ("macb: Add support for SiFive FU540-C000")
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 15a821f0

drivers/net/ethernet/cadence/macb_main.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -4088,7 +4088,7 @@ static int fu540_c000_clk_init(struct platform_device pdev, struct clk *pclk,
		mgmt->rate = 0;
		mgmt->hw.init = &init;

		*tx_clk = clk_register(NULL, &mgmt->hw);
		*tx_clk = devm_clk_register(&pdev->dev, &mgmt->hw);
		if (IS_ERR(*tx_clk))
		return PTR_ERR(*tx_clk);

		@@ -4416,7 +4416,6 @@ err_out_free_netdev:

		err_disable_clocks:
		clk_disable_unprepare(tx_clk);
		clk_unregister(tx_clk);
		clk_disable_unprepare(hclk);
		clk_disable_unprepare(pclk);
		clk_disable_unprepare(rx_clk);
		@@ -4446,7 +4445,6 @@ static int macb_remove(struct platform_device *pdev)
		pm_runtime_dont_use_autosuspend(&pdev->dev);
		if (!pm_runtime_suspended(&pdev->dev)) {
		clk_disable_unprepare(bp->tx_clk);
		clk_unregister(bp->tx_clk);
		clk_disable_unprepare(bp->hclk);
		clk_disable_unprepare(bp->pclk);
		clk_disable_unprepare(bp->rx_clk);

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