Messages in this thread Patch in this message |  | | Date | Thu, 30 Nov 2017 15:09:15 +0100 | From | Krzysztof Adamski <> | Subject | [PATCH] 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> --- drivers/base/regmap/regmap.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c index b9a779a4a739..d8806eac2708 100644 --- a/drivers/base/regmap/regmap.c +++ b/drivers/base/regmap/regmap.c @@ -2344,13 +2344,15 @@ 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; } -- 2.13.6
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