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Subject[PATCH 0/2] base/platform: Platform data and resources NULL handling
Hi all,

There is a bug in the MFD core code (drivers/mfd/mfd-core.c),
the mfd_add_device function does not check platform_data for NULL,
and thus always calls platform_device_add_data():

static int mfd_add_device(struct device *parent, int id, [...])
ret = platform_device_add_data(pdev,
cell->platform_data, cell->data_size);

The problem is that when cell->platform_data is NULL, the platform
core calls kmemdup(NULL, 0, ...), which returns a non-NULL result
(ZERO_SIZE_PTR), and the result is stored in the dev.platform_data.
This causes drivers to oops on a valid code:

if (pdata)
stuff = pdata->stuff;

Firstly I thought that I would fix the MFD core, but it appears
that the better approach would be to change device_add_data() call
behaviour, and thus make the core code more safe.

There are two patches: a patch that is necessary for the bug fix,
and a non-essential cleanup patch.


Anton Vorontsov

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