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regmap: use proper part of work_buf for storing val

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The map->work_buf is a buffer preallocated in __regmap_init() with size
allowing it to store all 3 parts of a buffer - reg, pad and val. While
reg and val parts are always properly setup before each transaction, the
pad part is left at its default value (zeros). Until it is overwritten,
that is.

_regmap_bus_read(), when calling _regmap_raw_read() uses beginning of
work_buf as a place to store data read. Usually that is fine but if
val_bits > reg_bits && pad_bits > 0, padding area of work_buf() may get
overwritten. Since padding is not zeroed before each transaction,
garbage will be used on next calls.

This patch moves the val pointer used for _regmap_raw_read() to point
to a part of work_buf intended for storing value read.

Signed-off-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Krzysztof Adamski 2017-11-30 15:09:15 +01:00 committed by Mark Brown
parent 4fbd8d194f
commit 4c90f297ff
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GPG key ID: 24D68B725D5487D0
1 changed files with 4 additions and 2 deletions
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6
drivers/base/regmap/regmap.c
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@ -2423,13 +2423,15 @@ static int _regmap_bus_read(void *context, unsigned int reg,
{
int ret;
struct regmap *map = context;
void *work_val = map->work_buf + map->format.reg_bytes +
map->format.pad_bytes;
if (!map->format.parse_val)
return -EINVAL;
ret = _regmap_raw_read(map, reg, map->work_buf, map->format.val_bytes);
ret = _regmap_raw_read(map, reg, work_val, map->format.val_bytes);
if (ret == 0)
*val = map->format.parse_val(map->work_buf);
*val = map->format.parse_val(work_val);
return ret;
}