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regmap: verify if register is writeable before writing operations 

regmap provides a couple of ways to validate the register range used.
a) maxim allowed register, b) writable/readable register tables,
c) callback function that can be provided by the driver to validate
a register. regmap framework should verify if registers
are writeable before every write operation. However this doesn't
seems to happen in every situation.

The method `_regmap_raw_write_impl` is only using the `writeable_reg`
callback to verify if register is writeable, ignoring the other two.
This can lead to undefined behaviour since this allows to write to
registers that could be declared un-writeable by using any other
option.

Change `_regmap_raw_write_impl` to use the `regmap_writeable` method
to verify if registers are writable before the write operation.

Signed-off-by: Nandor Han <nandor.han@vaisala.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
hifive-unleashed-5.2
Han Nandor 2019-04-02 08:01:22 +00:00 committed by Mark Brown
parent cc6a8d69ba
commit 8b9f9d4dc5
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1 changed files with 4 additions and 5 deletions
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9
drivers/base/regmap/regmap.c
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@ -1493,11 +1493,10 @@ static int _regmap_raw_write_impl(struct regmap *map, unsigned int reg,
WARN_ON(!map->bus);
/* Check for unwritable registers before we start */
if (map->writeable_reg)
for (i = 0; i < val_len / map->format.val_bytes; i++)
if (!map->writeable_reg(map->dev,
reg + regmap_get_offset(map, i)))
return -EINVAL;
for (i = 0; i < val_len / map->format.val_bytes; i++)
if (!regmap_writeable(map,
reg + regmap_get_offset(map, i)))
return -EINVAL;
if (!map->cache_bypass && map->format.parse_val) {
unsigned int ival;