[PATCH 1/5] mtd: maps: lantiq-flash: fix NULL pointer dereference on probe

[Simon Wunderlich <sw@simonwunderlich.de>]

Since commit 6145e07e9c77 ("mtd: lantiq-flash: Use
devm_platform_get_and_ioremap_resource()"), ltq_mtd_probe() stores the
ioremapped address in ltq_mtd->map->virt before ltq_mtd->map is
allocated. ltq_mtd comes from devm_kzalloc(), so map is still NULL at
that point and the probe dereferences a NULL pointer on every board
with a "lantiq,nor" node.

Allocate the map before mapping the resource.

Found by code inspection while porting a lantiq-flash change from
OpenWrt, which replaces this probe function downstream.

Fixes: 6145e07e9c77 ("mtd: lantiq-flash: Use devm_platform_get_and_ioremap_resource()")
Cc: stable@vger.kernel.org
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 drivers/mtd/maps/lantiq-flash.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/maps/lantiq-flash.c b/drivers/mtd/maps/lantiq-flash.c
index 80d467eba92a..5c2ace302b50 100644
--- a/drivers/mtd/maps/lantiq-flash.c
+++ b/drivers/mtd/maps/lantiq-flash.c
@@ -118,15 +118,15 @@ ltq_mtd_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, ltq_mtd);
 
-	ltq_mtd->map->virt = devm_platform_get_and_ioremap_resource(pdev, 0, &ltq_mtd->res);
-	if (IS_ERR(ltq_mtd->map->virt))
-		return PTR_ERR(ltq_mtd->map->virt);
-
 	ltq_mtd->map = devm_kzalloc(&pdev->dev, sizeof(struct map_info),
 				    GFP_KERNEL);
 	if (!ltq_mtd->map)
 		return -ENOMEM;
 
+	ltq_mtd->map->virt = devm_platform_get_and_ioremap_resource(pdev, 0, &ltq_mtd->res);
+	if (IS_ERR(ltq_mtd->map->virt))
+		return PTR_ERR(ltq_mtd->map->virt);
+
 	ltq_mtd->map->phys = ltq_mtd->res->start;
 	ltq_mtd->map->size = resource_size(ltq_mtd->res);
 
-- 
2.47.3