[PATCH] of: partitions: fix NULL pointer dereference in of_partition_fixup()

[Edoardo Scaglia]

When barebox 'internal devicetree' is not used and your board
registers a device that in turn registers a of_partition_fixup() (such
as at24 EEPROM), running the bootm command crashes barebox with a NULL
pointer dereference.

The error occurs when barebox applies Linux DTB fixups, specifically
in following lines of_partition_fixup():

    name = of_get_reproducible_name(cdev->device_node);
    np = of_find_node_by_reproducible_name(root, name);

since internal devicetree is not used cdev->device_node is NULL thus
of_get_reproducibile_name() returns NULL then NULL is passed as lookup
string to of_find_node_by_reproducible_name() which crashes trying to
dereference NULL pointer.

The culprit is commit fa9179444c36f9daf5010215cf8e4dcb3bd1ffb2.
Previously of_partition_fixup() returned -EINVAL when
cdev->device_node was NULL, apparently that check was lost along the
road.

Signed-off-by: Edoardo Scaglia <scaglia at amelchem.com>
---
 drivers/of/partition.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/of/partition.c b/drivers/of/partition.c
index 65c24c5426..b71716218b 100644
--- a/drivers/of/partition.c
+++ b/drivers/of/partition.c
@@ -235,6 +235,9 @@ static int of_partition_fixup(struct device_node *root, void *ctx)
 	struct device_node *np;
 	char *name;
 
+	if (!cdev->device_node)
+		return -EINVAL;
+
 	name = of_get_reproducible_name(cdev->device_node);
 	np = of_find_node_by_reproducible_name(root, name);
 	free(name);
-- 
2.30.0