[PATCH v3 0/3] mtd: maps: vmu-flash: Fix build and runtime errors

[PATCH v3 0/3] mtd: maps: vmu-flash: Fix build and runtime errors

[Florian Fuchs]

Hi all,

This small series fixes build and runtime errors in the vmu-flash driver
(enabled by CONFIG_MTD_VMU) and the related maple.h. These changes were
verified on real Dreamcast hardware with a physical VMU. The VMU can now
be successfully probed, read and written with MTD tools like mtdinfo and
mtd_debug. Previously, the driver failed to build or crashed during
probing.

        bash-5.3# mtdinfo /dev/mtd0
        mtd0
        Name:                           vmu2.1.0
        Type:                           mlc-nand
        Eraseblock size:                512 bytes
        Amount of eraseblocks:          256 (131072 bytes, 128.0 KiB)
        Minimum input/output unit size: 512 bytes
        Sub-page size:                  512 bytes
        Character device major/minor:   90:0
        Bad blocks are allowed:         true
        Device is writable:             true

Thanks,
Florian
---
v2->v3: Add Fixes tag to respective patches, fix subject to previous
        commits
v1->v2: Rebased patches and fixed the hotplug issues in other sh
        patches.

v2: https://lore.kernel.org/lkml/20260427114750.2480900-1-fuchsfl@gmail.com/
v1: https://lore.kernel.org/lkml/20251117224408.498449-1-fuchsfl@gmail.com/

The original v1 was postponed until the hotplug issue and other runtime
panics were fixed by the following patch:
"[PATCH v3] sh: maple: fix empty port handling":
https://lore.kernel.org/linux-sh/20260515181115.3244161-1-fuchsfl@gmail.com/

Using VMUs while some ports are empty requires the above patch.

Florian Fuchs (3):
  maple: fix build error due to missing include of linux/device.h
  mtd: maps: vmu-flash: fix fault in unaligned fixup
  mtd: maps: vmu-flash: fix NULL pointer dereference in initialization

 drivers/mtd/maps/vmu-flash.c | 7 ++++---
 include/linux/maple.h        | 3 +--
 2 files changed, 5 insertions(+), 5 deletions(-)


base-commit: 254f49634ee16a731174d2ae34bc50bd5f45e731
-- 
2.43.0

[PATCH v3 1/3] maple: fix build error due to missing include of linux/device.h

[Florian Fuchs]

The commit 313162d0b838 ("device.h: audit and cleanup users in main
include dir") removed the include linux/device.h from linux/maple.h,
which led to build errors as linux/maple.h embeds struct device via
struct maple_device. So restore this, as it otherwise results in errors:

./include/linux/maple.h:81:16: error: field 'dev' has incomplete type
  struct device dev;

Fixes: 313162d0b838 ("device.h: audit and cleanup users in main include dir")
Cc: stable@vger.kernel.org
Signed-off-by: Florian Fuchs <fuchsfl@gmail.com>
---
v2->v3: no functional change, reword commit message, align subject to
	main includedir, add Cc tag
v1->v2: no functional change, just rebase patch

v2: https://lore.kernel.org/lkml/20260427114750.2480900-2-fuchsfl@gmail.com/
v1: https://lore.kernel.org/lkml/20251117224408.498449-2-fuchsfl@gmail.com/

 include/linux/maple.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/linux/maple.h b/include/linux/maple.h
index 3be4e567473c..22f2930251ed 100644
--- a/include/linux/maple.h
+++ b/include/linux/maple.h
@@ -2,10 +2,9 @@
 #ifndef __LINUX_MAPLE_H
 #define __LINUX_MAPLE_H
 
+#include <linux/device.h>
 #include <mach/maple.h>
 
-struct device;
-
 /* Maple Bus command and response codes */
 enum maple_code {
 	MAPLE_RESPONSE_FILEERR =	-5,
-- 
2.43.0

[PATCH v3 2/3] mtd: maps: vmu-flash: fix fault in unaligned fixup

[Florian Fuchs]

Use kzalloc_obj() / kzalloc_objs() to allocate the memcard structs,
instead of kmalloc_obj() / kmalloc_objs() to prevent access to
uninitialized data.

Fixes runtime error: Fault in unaligned fixup: 0000 [#1] at
mtd_get_fact_prot_info.

Fixes: 47a72688fae7 ("mtd: flash mapping support for Dreamcast VMU.")
Cc: stable@vger.kernel.org
Signed-off-by: Florian Fuchs <fuchsfl@gmail.com>
---
v2->v3: no functional change, add Fixes, Cc tag according to feedback
v1->v2: no functional change, just rebased.

v2: https://lore.kernel.org/lkml/20260427114750.2480900-3-fuchsfl@gmail.com/
v1: https://lore.kernel.org/lkml/20251117224408.498449-3-fuchsfl@gmail.com/

 drivers/mtd/maps/vmu-flash.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/maps/vmu-flash.c b/drivers/mtd/maps/vmu-flash.c
index 75e06d249ce9..b76d0609d1b7 100644
--- a/drivers/mtd/maps/vmu-flash.c
+++ b/drivers/mtd/maps/vmu-flash.c
@@ -609,7 +609,7 @@ static int vmu_connect(struct maple_device *mdev)
 
 	basic_flash_data = be32_to_cpu(mdev->devinfo.function_data[c - 1]);
 
-	card = kmalloc_obj(struct memcard);
+	card = kzalloc_obj(struct memcard);
 	if (!card) {
 		error = -ENOMEM;
 		goto fail_nomem;
@@ -627,13 +627,13 @@ static int vmu_connect(struct maple_device *mdev)
 	* Not sure there are actually any multi-partition devices in the
 	* real world, but the hardware supports them, so, so will we
 	*/
-	card->parts = kmalloc_objs(struct vmupart, card->partitions);
+	card->parts = kzalloc_objs(struct vmupart, card->partitions);
 	if (!card->parts) {
 		error = -ENOMEM;
 		goto fail_partitions;
 	}
 
-	card->mtd = kmalloc_objs(struct mtd_info, card->partitions);
+	card->mtd = kzalloc_objs(struct mtd_info, card->partitions);
 	if (!card->mtd) {
 		error = -ENOMEM;
 		goto fail_mtd_info;
-- 
2.43.0

[PATCH v3 3/3] mtd: maps: vmu-flash: fix NULL pointer dereference in initialization

[Florian Fuchs]

The mtd_info contains a struct device, which must be linked to its
parent. Without this, the initialization of the MTD fails with a NULL
pointer dereference.

Fixes: 47a72688fae7 ("mtd: flash mapping support for Dreamcast VMU.")
Cc: stable@vger.kernel.org
Signed-off-by: Florian Fuchs <fuchsfl@gmail.com>
---
v2->v3: no functional change, added Fixes, Cc tag according to feedback
v1->v2: no functional change

v2: https://lore.kernel.org/lkml/20260427114750.2480900-4-fuchsfl@gmail.com/
v1: https://lore.kernel.org/lkml/20251117224408.498449-4-fuchsfl@gmail.com/

 drivers/mtd/maps/vmu-flash.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/mtd/maps/vmu-flash.c b/drivers/mtd/maps/vmu-flash.c
index b76d0609d1b7..10244e6731d0 100644
--- a/drivers/mtd/maps/vmu-flash.c
+++ b/drivers/mtd/maps/vmu-flash.c
@@ -547,6 +547,7 @@ static void vmu_queryblocks(struct mapleq *mq)
 	mpart->partition = card->partition;
 	mtd_cur->priv = mpart;
 	mtd_cur->owner = THIS_MODULE;
+	mtd_cur->dev.parent = &mdev->dev;
 
 	pcache = kzalloc_obj(struct vmu_cache);
 	if (!pcache)
-- 
2.43.0

Re: [PATCH v3 0/3] mtd: maps: vmu-flash: Fix build and runtime errors

[Miquel Raynal]

Hi Florian,

On 18/05/2026 at 13:45:18 +02, Florian Fuchs <fuchsfl@gmail.com> wrote:

> Hi all,
>
> This small series fixes build and runtime errors in the vmu-flash driver
> (enabled by CONFIG_MTD_VMU) and the related maple.h. These changes were
> verified on real Dreamcast hardware with a physical VMU. The VMU can now
> be successfully probed, read and written with MTD tools like mtdinfo and
> mtd_debug. Previously, the driver failed to build or crashed during
> probing.
>
>         bash-5.3# mtdinfo /dev/mtd0
>         mtd0
>         Name:                           vmu2.1.0
>         Type:                           mlc-nand
>         Eraseblock size:                512 bytes
>         Amount of eraseblocks:          256 (131072 bytes, 128.0 KiB)
>         Minimum input/output unit size: 512 bytes
>         Sub-page size:                  512 bytes
>         Character device major/minor:   90:0
>         Bad blocks are allowed:         true
>         Device is writable:             true
>
> Thanks,
> Florian
> ---

I believe there is no issue in applying patches 2 and 3 on top of the
mtd tree and let whoever is responsible take patch 1. If I get an ack I
can also carry patch 1 through the mtd tree. Without more feedback I
plan on applying patches 2 and 3 in the coming weeks.

Thanks,
Miquèl