Input: ims-pcu - check record size in ims_pcu_flash_firmware()

commit a95ef01 upstream.

The "len" variable comes from the firmware and we generally do
trust firmware, but it's always better to double check.  If the "len"
is too large it could result in memory corruption when we do
"memcpy(fragment->data, rec->data, len);"

Fixes: 628329d ("Input: add IMS Passenger Control Unit driver")
Signed-off-by: Dan Carpenter <[email protected]>
Link: https://lore.kernel.org/r/131fd1ae92c828ee9f4fa2de03d8c210ae1f3524.1748463049.git.dan.carpenter@linaro.org
Cc: [email protected]
Signed-off-by: Dmitry Torokhov <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
(cherry picked from commit c1b9d140b0807c6aee4bb53e1bfa4e391e3dc204)
Signed-off-by: Alok Tiwari <[email protected]>

Author: Dan Carpenter

drivers/input/misc/ims-pcu.c

@@ -845,6 +845,12 @@ static int ims_pcu_flash_firmware(struct ims_pcu *pcu,
 		addr = be32_to_cpu(rec->addr) / 2;
 		len = be16_to_cpu(rec->len);
 
+		if (len > sizeof(pcu->cmd_buf) - 1 - sizeof(*fragment)) {
+			dev_err(pcu->dev,
+				"Invalid record length in firmware: %d\n", len);
+			return -EINVAL;
+		}
+
 		fragment = (void *)&pcu->cmd_buf[1];
 		put_unaligned_le32(addr, &fragment->addr);
 		fragment->len = len;