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drm/imx: fix use after free

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Component driver structures allocated with devm_kmalloc() in bind() are
freed automatically after unbind(). Since the contained drm structures
are accessed afterwards in drm_mode_config_cleanup(), move the
allocation into probe() to extend the driver structure's lifetime to the
lifetime of the device. This should eventually be changed to use drm
resource managed allocations with lifetime of the drm device.

We also need to ensure that all componets are available during the
unbind() so we need to call component_unbind_all() before we free
non-devres resources like planes.

Note this patch fixes the the use after free bug but introduces a
possible boot loop issue. The issue is triggered if the HDMI support is
enabled and a component driver always return -EPROBE_DEFER, see
discussion [1] for more details.

[1] https://lkml.org/lkml/2020/3/24/1467

Fixes: 17b5001b51 ("imx-drm: convert to componentised device support")
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
[m.felsch@pengutronix: fix imx_tve_probe()]
[m.felsch@pengutronix: resort component_unbind_all())
[m.felsch@pengutronix: adapt commit message]
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
This commit is contained in:
Philipp Zabel
2020-06-11 14:43:31 +02:00
parent b3a9e3b962
commit ba807c94f6
6 changed files with 52 additions and 32 deletions
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15
drivers/gpu/drm/imx/imx-ldb.c
View File

@@ -590,9 +590,8 @@ static int imx_ldb_bind(struct device *dev, struct device *master, void *data)
int ret;
int i;
imx_ldb = devm_kzalloc(dev, sizeof(*imx_ldb), GFP_KERNEL);
if (!imx_ldb)
return -ENOMEM;
imx_ldb = dev_get_drvdata(dev);
memset(imx_ldb, 0, sizeof(*imx_ldb));
imx_ldb->regmap = syscon_regmap_lookup_by_phandle(np, "gpr");
if (IS_ERR(imx_ldb->regmap)) {
@@ -700,8 +699,6 @@ static int imx_ldb_bind(struct device *dev, struct device *master, void *data)
}
}
dev_set_drvdata(dev, imx_ldb);
return 0;
free_child:
@@ -733,6 +730,14 @@ static const struct component_ops imx_ldb_ops = {
static int imx_ldb_probe(struct platform_device *pdev)
{
struct imx_ldb *imx_ldb;
imx_ldb = devm_kzalloc(&pdev->dev, sizeof(*imx_ldb), GFP_KERNEL);
if (!imx_ldb)
return -ENOMEM;
platform_set_drvdata(pdev, imx_ldb);
return component_add(&pdev->dev, &imx_ldb_ops);
}