[PATCH 1/3] Input: atmel_mxt_ts - fix boundary check in mxt_prepare_cfg_mem

[Dmitry Torokhov]

When a configuration file provides an object size that is larger than the
driver's known mxt_obj_size(object), the driver intends to discard the
extra bytes.

The loop iterates using for (i = 0; i < size; i++). Inside the loop, the
condition to skip processing extra bytes is:

    if (i > mxt_obj_size(object))
        continue;

Since i is a 0-based index, the valid indices for the object are 0 through
mxt_obj_size(object) - 1.

When i == mxt_obj_size(object), the condition evaluates to false, and the
code processes the byte instead of discarding it.

This causes the code to calculate byte_offset = reg + i - cfg->start_ofs
and writes the byte there, overwriting exactly one byte of the adjacent
instance or object.

Update the boundary check to skip extra bytes correctly by using >=.

Fixes: 50a77c658b80 ("Input: atmel_mxt_ts - download device config using firmware loader")
Cc: stable@xxxxxxxxxxxxxxx
Assisted-by: Gemini:gemini-3.1-pro
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
---
 drivers/input/touchscreen/atmel_mxt_ts.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index d62bf2c95578..28b2bd889c70 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -1503,7 +1503,7 @@ static int mxt_prepare_cfg_mem(struct mxt_data *data, struct mxt_cfg *cfg)
 			}
 			cfg->raw_pos += offset;
 
-			if (i > mxt_obj_size(object))
+			if (i >= mxt_obj_size(object))
 				continue;
 
 			byte_offset = reg + i - cfg->start_ofs;
-- 
2.54.0.545.g6539524ca2-goog