regmap-irq: Fix offset/index mismatch in read_sub_irq_data()

We need to divide the sub-irq status register offset by register
stride to get an index for the status buffer to avoid an out of
bounds write when the register stride is greater than 1.

Fixes: a2d21848d921 ("regmap: regmap-irq: Add main status register support")
Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
Link: https://lore.kernel.org/r/20220620200644.1961936-3-aidanmacdonald.0x0@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/base/regmap/regmap-irq.c b/drivers/base/regmap/regmap-irq.c
index 4f785bc7981cd86579fb09c7ad1bc652d643096c..a6db605707b0007d8b13bbcb891a2a0d4535e24d 100644 (file)
--- a/drivers/base/regmap/regmap-irq.c
+++ b/drivers/base/regmap/regmap-irq.c
@@ -387,6 +387,7 @@ static inline int read_sub_irq_data(struct regmap_irq_chip_data *data,
                subreg = &chip->sub_reg_offsets[b];
                for (i = 0; i < subreg->num_regs; i++) {
                        unsigned int offset = subreg->offset[i];
+                       unsigned int index = offset / map->reg_stride;
 
                        if (chip->not_fixed_stride)
                                ret = regmap_read(map,
@@ -395,7 +396,7 @@ static inline int read_sub_irq_data(struct regmap_irq_chip_data *data,
                        else
                                ret = regmap_read(map,
                                                chip->status_base + offset,
-                                               &data->status_buf[offset]);
+                                               &data->status_buf[index]);
 
                        if (ret)
                                break;