drm/meson: Uninstall IRQ handler

[ Upstream commit 2d8f92897ad816f5dda54b2ed2fd9f2d7cb1abde ]

meson_drv_unbind() doesn't unregister the IRQ handler, which can lead to
use-after-free if the IRQ fires after unbind:

[   64.656876] Unable to handle kernel paging request at virtual address ffff000011706dbc
...
[   64.662001] pc : meson_irq+0x18/0x30 [meson_drm]

I'm assuming that a similar problem could happen on the error path of
bind(), so uninstall the IRQ handler there as well.

Fixes: bbbe775ec5b5 ("drm: Add support for Amlogic Meson Graphic Controller")
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190322152657.13752-2-jean-philippe.brucker@arm.com
Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>

diff --git a/drivers/gpu/drm/meson/meson_drv.c b/drivers/gpu/drm/meson/meson_drv.c
index 4a72fa5..588b3b0 100644 (file)
--- a/drivers/gpu/drm/meson/meson_drv.c
+++ b/drivers/gpu/drm/meson/meson_drv.c
@@ -300,10 +300,12 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
 
        ret = drm_dev_register(drm, 0);
        if (ret)
-               goto free_drm;
+               goto uninstall_irq;
 
        return 0;
 
+uninstall_irq:
+       drm_irq_uninstall(drm);
 free_drm:
        drm_dev_put(drm);
 
@@ -321,6 +323,7 @@ static void meson_drv_unbind(struct device *dev)
        struct drm_device *drm = priv->drm;
 
        drm_dev_unregister(drm);
+       drm_irq_uninstall(drm);
        drm_kms_helper_poll_fini(drm);
        drm_fbdev_cma_fini(priv->fbdev);
        drm_mode_config_cleanup(drm);