From 1a07a94b47b1f528f39c3e6187b5eaf02efe44ea Mon Sep 17 00:00:00 2001 From: Ondrej Jirman Date: Sat, 6 Apr 2019 01:30:48 +0200 Subject: drm/sun4i: tcon top: Fix NULL/invalid pointer dereference in sun8i_tcon_top_un/bind There are two problems here: 1. Not all clk_data->hws[] need to be initialized, depending on various configured quirks. This leads to NULL ptr deref in clk_hw_unregister_gate() in sun8i_tcon_top_unbind() 2. If there is error when registering the clk_data->hws[], err_unregister_gates error path will try to unregister IS_ERR()=true (invalid) pointer. For problem (1) I have this stack trace: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008 Call trace: clk_hw_unregister+0x8/0x18 clk_hw_unregister_gate+0x14/0x28 sun8i_tcon_top_unbind+0x2c/0x60 component_unbind.isra.4+0x2c/0x50 component_bind_all+0x1d4/0x230 sun4i_drv_bind+0xc4/0x1a0 try_to_bring_up_master+0x164/0x1c0 __component_add+0xa0/0x168 component_add+0x10/0x18 sun8i_dw_hdmi_probe+0x18/0x20 platform_drv_probe+0x3c/0x70 really_probe+0xcc/0x278 driver_probe_device+0x34/0xa8 Problem (2) was identified by head scratching. Signed-off-by: Ondrej Jirman Signed-off-by: Maxime Ripard Link: https://patchwork.freedesktop.org/patch/msgid/20190405233048.3823-1-megous@megous.com --- drivers/gpu/drm/sun4i/sun8i_tcon_top.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'drivers/gpu/drm/sun4i') diff --git a/drivers/gpu/drm/sun4i/sun8i_tcon_top.c b/drivers/gpu/drm/sun4i/sun8i_tcon_top.c index fc36e0c10a37..b1e7c76e9c17 100644 --- a/drivers/gpu/drm/sun4i/sun8i_tcon_top.c +++ b/drivers/gpu/drm/sun4i/sun8i_tcon_top.c @@ -227,7 +227,7 @@ static int sun8i_tcon_top_bind(struct device *dev, struct device *master, err_unregister_gates: for (i = 0; i < CLK_NUM; i++) - if (clk_data->hws[i]) + if (!IS_ERR_OR_NULL(clk_data->hws[i])) clk_hw_unregister_gate(clk_data->hws[i]); clk_disable_unprepare(tcon_top->bus); err_assert_reset: @@ -245,7 +245,8 @@ static void sun8i_tcon_top_unbind(struct device *dev, struct device *master, of_clk_del_provider(dev->of_node); for (i = 0; i < CLK_NUM; i++) - clk_hw_unregister_gate(clk_data->hws[i]); + if (clk_data->hws[i]) + clk_hw_unregister_gate(clk_data->hws[i]); clk_disable_unprepare(tcon_top->bus); reset_control_assert(tcon_top->rst); -- cgit v1.2.3