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[next] iio: cros_ec: Avoid -Wflex-array-member-not-at-end warning

Message ID Z9dy43vUUh4goi-Q@kspp (mailing list archive)
State New
Headers show
Series [next] iio: cros_ec: Avoid -Wflex-array-member-not-at-end warning | expand

Commit Message

Gustavo A. R. Silva March 17, 2025, 12:54 a.m. UTC
-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.

Use the `DEFINE_RAW_FLEX()` helper for an on-stack definition of
a flexible structure where the size of the flexible-array member
is known at compile-time, and refactor the rest of the code,
accordingly.

So, with these changes, fix the following warning:

drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c:39:40: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---

This looks pretty much like the following patch for RTC:

https://lore.kernel.org/linux-hardening/Z9PpPg06OK8ghNvm@kspp/

Thanks

 .../cros_ec_sensors/cros_ec_sensors_core.c    | 27 +++++++------------
 1 file changed, 10 insertions(+), 17 deletions(-)

Comments

Tzung-Bi Shih March 17, 2025, 1:32 a.m. UTC | #1
On Mon, Mar 17, 2025 at 11:24:59AM +1030, Gustavo A. R. Silva wrote:
>  static int cros_ec_get_host_cmd_version_mask(struct cros_ec_device *ec_dev,
>  					     u16 cmd_offset, u16 cmd, u32 *mask)
>  {
> +	DEFINE_RAW_FLEX(struct cros_ec_command, buf, data,
> +			sizeof(struct ec_response_get_cmd_versions));

max(sizeof(struct ec_params_get_cmd_versions),
    sizeof(struct ec_response_get_cmd_versions))?
Gustavo A. R. Silva March 17, 2025, 4:40 a.m. UTC | #2
On 17/03/25 12:02, Tzung-Bi Shih wrote:
> On Mon, Mar 17, 2025 at 11:24:59AM +1030, Gustavo A. R. Silva wrote:
>>   static int cros_ec_get_host_cmd_version_mask(struct cros_ec_device *ec_dev,
>>   					     u16 cmd_offset, u16 cmd, u32 *mask)
>>   {
>> +	DEFINE_RAW_FLEX(struct cros_ec_command, buf, data,
>> +			sizeof(struct ec_response_get_cmd_versions));
> 
> max(sizeof(struct ec_params_get_cmd_versions),
>      sizeof(struct ec_response_get_cmd_versions))?

I considered that, but DEFINE_RAW_FLEX() complains about it due to the

_Static_assert(__builtin_constant_p(count),				\
		       "onstack flex array members require compile-time const count");

--
Gustavo
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Patch

diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c
index 7751d6f69b12..760a07f64390 100644
--- a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c
+++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c
@@ -34,25 +34,18 @@ 
 static int cros_ec_get_host_cmd_version_mask(struct cros_ec_device *ec_dev,
 					     u16 cmd_offset, u16 cmd, u32 *mask)
 {
+	DEFINE_RAW_FLEX(struct cros_ec_command, buf, data,
+			sizeof(struct ec_response_get_cmd_versions));
 	int ret;
-	struct {
-		struct cros_ec_command msg;
-		union {
-			struct ec_params_get_cmd_versions params;
-			struct ec_response_get_cmd_versions resp;
-		};
-	} __packed buf = {
-		.msg = {
-			.command = EC_CMD_GET_CMD_VERSIONS + cmd_offset,
-			.insize = sizeof(struct ec_response_get_cmd_versions),
-			.outsize = sizeof(struct ec_params_get_cmd_versions)
-			},
-		.params = {.cmd = cmd}
-	};
-
-	ret = cros_ec_cmd_xfer_status(ec_dev, &buf.msg);
+
+	buf->command = EC_CMD_GET_CMD_VERSIONS + cmd_offset;
+	buf->insize = sizeof(struct ec_response_get_cmd_versions);
+	buf->outsize = sizeof(struct ec_params_get_cmd_versions);
+	((struct ec_params_get_cmd_versions *)buf->data)->cmd = cmd;
+
+	ret = cros_ec_cmd_xfer_status(ec_dev, buf);
 	if (ret >= 0)
-		*mask = buf.resp.version_mask;
+		*mask = ((struct ec_response_get_cmd_versions *)buf->data)->version_mask;
 	return ret;
 }