linux-kernel - [PATCH] comedi: check data length for INSN_CONFIG_GET_PWM

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Message-Id: <20230103151127.19287-1-abbotti@mev.co.uk>
Date:   Tue,  3 Jan 2023 15:11:27 +0000
From:   Ian Abbott <abbotti@....co.uk>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ian Abbott <abbotti@....co.uk>,
        H Hartley Sweeten <hsweeten@...ionengravers.com>
Subject: [PATCH] comedi: check data length for INSN_CONFIG_GET_PWM_OUTPUT

Comedi INSN_CONFIG instructions have different expected instructtion
data lengths depending on the type of configuration instruction
specified by the first word of data.  This is checked by
`check_insn_config_length()`.  There are a few configuration
instructions whose data lengths are not currently checked, usually for
rare configuration instructions that are implemented differently by
different drivers.  For unknown configuration instructions, the function
logs a warning and accepts the specified data length.

The `INSN_CONFIG_GET_PWM_OUTPUT` configuration instruction length is not
currently checked, but all the places it is currently used expect a data
length of 3.  (These places are `ni_get_pwm_config()` in
"ni_mio_common.c", and `pci1760_pwm_insn_config()` in "adv_pci1760.c".)
Make this length official by checking it in
`check_insn_config_length()`.

Signed-off-by: Ian Abbott <abbotti@....co.uk>
---
 drivers/comedi/comedi_fops.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/comedi/comedi_fops.c b/drivers/comedi/comedi_fops.c
index e2114bcf815a..b982903aaa46 100644
--- a/drivers/comedi/comedi_fops.c
+++ b/drivers/comedi/comedi_fops.c
@@ -1215,6 +1215,7 @@ static int check_insn_config_length(struct comedi_insn *insn,
 	case INSN_CONFIG_GET_CLOCK_SRC:
 	case INSN_CONFIG_SET_OTHER_SRC:
 	case INSN_CONFIG_GET_COUNTER_STATUS:
+	case INSN_CONFIG_GET_PWM_OUTPUT:
 	case INSN_CONFIG_PWM_SET_H_BRIDGE:
 	case INSN_CONFIG_PWM_GET_H_BRIDGE:
 	case INSN_CONFIG_GET_HARDWARE_BUFFER_SIZE:
-- 
2.35.1