[PATCH] drm/tiny: sharp-memory: reject devices without match data

[PATCH] drm/tiny: sharp-memory: reject devices without match data

[Jiale Yao]

SPI driver_override allows a device to bind to this driver without
matching either the OF or SPI device ID table. In that case,
spi_get_device_match_data() returns NULL.

sharp_memory_probe() immediately dereferences the returned display mode
to calculate the pitch and transmit buffer size, causing a NULL pointer
dereference.

Commit 572a00852635 ("iio: dac: ad5686: missing NULL check on match
data") fixed the same driver_override issue in another SPI driver.
Reject devices without match data before using the display mode.

Fixes: b8f9f21716fe ("drm/tiny: Add driver for Sharp Memory LCD")
Cc: stable@vger.kernel.org
Signed-off-by: Jiale Yao <yaojiale02@163.com>
---
 drivers/gpu/drm/tiny/sharp-memory.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/tiny/sharp-memory.c b/drivers/gpu/drm/tiny/sharp-memory.c
index 7efd7b567f3b..049e98f657f3 100644
--- a/drivers/gpu/drm/tiny/sharp-memory.c
+++ b/drivers/gpu/drm/tiny/sharp-memory.c
@@ -557,6 +557,8 @@ static int sharp_memory_probe(struct spi_device *spi)
 
 	drm->mode_config.funcs = &sharp_memory_mode_config_funcs;
 	smd->mode = spi_get_device_match_data(spi);
+	if (!smd->mode)
+		return -ENODATA;
 
 	smd->pitch = (SHARP_ADDR_PERIOD + smd->mode->hdisplay + SHARP_DUMMY_PERIOD) / 8;
 	smd->tx_buffer_size = (SHARP_MODE_PERIOD +
-- 
2.34.1

Re: [PATCH] drm/tiny: sharp-memory: reject devices without match data

[Uwe Kleine-König]

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Hello,

On Fri, Sep 25, 2026 at 08:36:08PM +0800, Jiale Yao wrote:
> SPI driver_override allows a device to bind to this driver without
> matching either the OF or SPI device ID table. In that case,
> spi_get_device_match_data() returns NULL.
> 
> sharp_memory_probe() immediately dereferences the returned display mode
> to calculate the pitch and transmit buffer size, causing a NULL pointer
> dereference.
> 
> Commit 572a00852635 ("iio: dac: ad5686: missing NULL check on match
> data") fixed the same driver_override issue in another SPI driver.
> Reject devices without match data before using the display mode.
> 
> Fixes: b8f9f21716fe ("drm/tiny: Add driver for Sharp Memory LCD")
> Cc: stable@vger.kernel.org
> Signed-off-by: Jiale Yao <yaojiale02@163.com>

Note there is an effort to make it impossible to use driver_override in
the core and only allow a few dedicated drivers. (See
https://lore.kernel.org/lkml/20260922-driver-override-opt-out-v1-0-58c35ded3b83@nvidia.com/)

That should make your effort to implement that check in all the driver
redundant.

Best regards
Uwe

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