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Input: sparse-keymap - use a managed allocation for keymap copy

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Some platform drivers use devm_input_allocate_device() together with
sparse_keymap_setup() in their .probe callbacks.  While using the former
simplifies error handling, using the latter necessitates calling
sparse_keymap_free() in the error path and upon module unloading to
avoid leaking the copy of the keymap allocated by sparse_keymap_setup().

To help prevent such leaks and enable simpler error handling, make
sparse_keymap_setup() use devm_kmemdup() to create the keymap copy so
that it gets automatically freed.

This works for both managed and non-managed input devices as the keymap
is freed after the last reference to the input device is dropped.

Note that actions previously taken by sparse_keymap_free(), i.e. taking
the input device's mutex and zeroing its keycode and keycodemax fields,
are now redundant because the managed keymap will always be freed after
the input device is unregistered.

Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Michał Kępień 2017-03-08 09:20:10 -08:00 committed by Dmitry Torokhov
parent c470abd4fd
commit fabeb165af
1 changed files with 9 additions and 30 deletions
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39
drivers/input/sparse-keymap.c
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@ -160,12 +160,12 @@ static int sparse_keymap_setkeycode(struct input_dev *dev,
* @keymap: Keymap in form of array of &key_entry structures ending
* with %KE_END type entry
* @setup: Function that can be used to adjust keymap entries
* depending on device's deeds, may be %NULL
* depending on device's needs, may be %NULL
*
* The function calculates size and allocates copy of the original
* keymap after which sets up input device event bits appropriately.
* Before destroying input device allocated keymap should be freed
* with a call to sparse_keymap_free().
* The allocated copy of the keymap is automatically freed when it
* is no longer needed.
*/
int sparse_keymap_setup(struct input_dev *dev,
const struct key_entry *keymap,
@ -180,19 +180,18 @@ int sparse_keymap_setup(struct input_dev *dev,
for (e = keymap; e->type != KE_END; e++)
map_size++;
map = kcalloc(map_size, sizeof(struct key_entry), GFP_KERNEL);
map = devm_kmemdup(&dev->dev, keymap, map_size * sizeof(*map),
GFP_KERNEL);
if (!map)
return -ENOMEM;
memcpy(map, keymap, map_size * sizeof(struct key_entry));
for (i = 0; i < map_size; i++) {
entry = &map[i];
if (setup) {
error = setup(dev, entry);
if (error)
goto err_out;
return error;
}
switch (entry->type) {
@ -221,10 +220,6 @@ int sparse_keymap_setup(struct input_dev *dev,
dev->setkeycode = sparse_keymap_setkeycode;
return 0;
err_out:
kfree(map);
return error;
}
EXPORT_SYMBOL(sparse_keymap_setup);
@ -232,29 +227,13 @@ EXPORT_SYMBOL(sparse_keymap_setup);
* sparse_keymap_free - free memory allocated for sparse keymap
* @dev: Input device using sparse keymap
*
* This function is used to free memory allocated by sparse keymap
* This function used to free memory allocated by sparse keymap
* in an input device that was set up by sparse_keymap_setup().
* NOTE: It is safe to cal this function while input device is
* still registered (however the drivers should care not to try to
* use freed keymap and thus have to shut off interrupts/polling
* before freeing the keymap).
* Since sparse_keymap_setup() now uses a managed allocation for the
* keymap copy, use of this function is deprecated.
*/
void sparse_keymap_free(struct input_dev *dev)
{
unsigned long flags;
/*
* Take event lock to prevent racing with input_get_keycode()
* and input_set_keycode() if we are called while input device
* is still registered.
*/
spin_lock_irqsave(&dev->event_lock, flags);
kfree(dev->keycode);
dev->keycode = NULL;
dev->keycodemax = 0;
spin_unlock_irqrestore(&dev->event_lock, flags);
}
EXPORT_SYMBOL(sparse_keymap_free);