| Message ID | Z-azMlPnP7nPPJrY@kspp |
|---|---|
| State | New |
| Headers | show |
| Series | [next] leds: Avoid -Wflex-array-member-not-at-end warning | expand |
Hi Gustavo, On 2025-03-28 08:33:22-0600, Gustavo A. R. Silva wrote: > -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/leds/leds-cros_ec.c:70:40: 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> > --- > drivers/leds/leds-cros_ec.c | 26 +++++++++++--------------- > 1 file changed, 11 insertions(+), 15 deletions(-) > > diff --git a/drivers/leds/leds-cros_ec.c b/drivers/leds/leds-cros_ec.c > index 275522b81ea5..6eab0474f52d 100644 > --- a/drivers/leds/leds-cros_ec.c > +++ b/drivers/leds/leds-cros_ec.c > @@ -66,24 +66,20 @@ static int cros_ec_led_send_cmd(struct cros_ec_device *cros_ec, > union cros_ec_led_cmd_data *arg) > { > int ret; > - struct { > - struct cros_ec_command msg; > - union cros_ec_led_cmd_data data; > - } __packed buf = { > - .msg = { > - .version = 1, > - .command = EC_CMD_LED_CONTROL, > - .insize = sizeof(arg->resp), > - .outsize = sizeof(arg->req), > - }, > - .data.req = arg->req > - }; > - > - ret = cros_ec_cmd_xfer_status(cros_ec, &buf.msg); > + DEFINE_RAW_FLEX(struct cros_ec_command, msg, data, > + sizeof(union cros_ec_led_cmd_data)); > + > + msg->version = 1; > + msg->command = EC_CMD_LED_CONTROL; > + msg->insize = sizeof(arg->resp); > + msg->outsize = sizeof(arg->req); > + *(struct ec_params_led_control *)msg->data = arg->req; To be honest this looks really ugly and it's not at all obvious what is going on. We have the utility function cros_ec_cmd() which would be the nicer alternative. (Without having verified that it avoids the warning). While it is slightly more expensive, I don't think it matters. And if it does, the helper can be optimized. (The same goes for my other cros_ec drivers) > + > + ret = cros_ec_cmd_xfer_status(cros_ec, msg); > if (ret < 0) > return ret; > > - arg->resp = buf.data.resp; > + arg->resp = *(struct ec_response_led_control *)msg->data; > > return 0; > } Thomas
Hi! On 2025-03-28 12:51:02-0600, Gustavo A. R. Silva wrote: > On 28/03/25 12:31, Thomas Weißschuh wrote: > > On 2025-03-28 08:33:22-0600, Gustavo A. R. Silva wrote: > > > -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/leds/leds-cros_ec.c:70:40: 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> > > > --- > > > drivers/leds/leds-cros_ec.c | 26 +++++++++++--------------- > > > 1 file changed, 11 insertions(+), 15 deletions(-) > > > > > > diff --git a/drivers/leds/leds-cros_ec.c b/drivers/leds/leds-cros_ec.c > > > index 275522b81ea5..6eab0474f52d 100644 > > > --- a/drivers/leds/leds-cros_ec.c > > > +++ b/drivers/leds/leds-cros_ec.c > > > @@ -66,24 +66,20 @@ static int cros_ec_led_send_cmd(struct cros_ec_device *cros_ec, > > > union cros_ec_led_cmd_data *arg) > > > { > > > int ret; > > > - struct { > > > - struct cros_ec_command msg; > > > - union cros_ec_led_cmd_data data; > > > - } __packed buf = { > > > - .msg = { > > > - .version = 1, > > > - .command = EC_CMD_LED_CONTROL, > > > - .insize = sizeof(arg->resp), > > > - .outsize = sizeof(arg->req), > > > - }, > > > - .data.req = arg->req > > > - }; > > > - > > > - ret = cros_ec_cmd_xfer_status(cros_ec, &buf.msg); > > > + DEFINE_RAW_FLEX(struct cros_ec_command, msg, data, > > > + sizeof(union cros_ec_led_cmd_data)); > > > + > > > + msg->version = 1; > > > + msg->command = EC_CMD_LED_CONTROL; > > > + msg->insize = sizeof(arg->resp); > > > + msg->outsize = sizeof(arg->req); > > > + *(struct ec_params_led_control *)msg->data = arg->req; > > > > To be honest this looks really ugly and it's not at all obvious what is > > We can do something like this, instead: > > diff --git a/drivers/leds/leds-cros_ec.c b/drivers/leds/leds-cros_ec.c > index 275522b81ea5..c7235f4e577b 100644 > --- a/drivers/leds/leds-cros_ec.c > +++ b/drivers/leds/leds-cros_ec.c > @@ -66,24 +66,24 @@ static int cros_ec_led_send_cmd(struct cros_ec_device *cros_ec, > union cros_ec_led_cmd_data *arg) > { > int ret; > - struct { > - struct cros_ec_command msg; > - union cros_ec_led_cmd_data data; > - } __packed buf = { > - .msg = { > - .version = 1, > - .command = EC_CMD_LED_CONTROL, > - .insize = sizeof(arg->resp), > - .outsize = sizeof(arg->req), > - }, > - .data.req = arg->req > - }; > - > - ret = cros_ec_cmd_xfer_status(cros_ec, &buf.msg); > + DEFINE_RAW_FLEX(struct cros_ec_command, msg, data, > + sizeof(union cros_ec_led_cmd_data)); > + struct ec_params_led_control *req = > + (struct ec_params_led_control *)msg->data; > + struct ec_response_led_control *resp = > + (struct ec_response_led_control *)msg->data; > + > + msg->version = 1; > + msg->command = EC_CMD_LED_CONTROL; > + msg->insize = sizeof(arg->resp); > + msg->outsize = sizeof(arg->req); > + *req = arg->req; > + > + ret = cros_ec_cmd_xfer_status(cros_ec, msg); > if (ret < 0) > return ret; > > - arg->resp = buf.data.resp; > + arg->resp = *resp; > > return 0; > } My issue was with the general usage of DEFINE_RAW_FLEX(), the reply was placed badly. For somebody not knowing this construct it's not clear what is happening under the hood. It's probably fine in a regular header file with some explanation, but in a random driver it looks off. The following is what I had in mind. Now actually tested. --- a/drivers/leds/leds-cros_ec.c +++ b/drivers/leds/leds-cros_ec.c @@ -60,31 +60,18 @@ static inline struct cros_ec_led_priv *cros_ec_led_cdev_to_priv(struct led_class union cros_ec_led_cmd_data { struct ec_params_led_control req; struct ec_response_led_control resp; -} __packed; +}; static int cros_ec_led_send_cmd(struct cros_ec_device *cros_ec, union cros_ec_led_cmd_data *arg) { int ret; - struct { - struct cros_ec_command msg; - union cros_ec_led_cmd_data data; - } __packed buf = { - .msg = { - .version = 1, - .command = EC_CMD_LED_CONTROL, - .insize = sizeof(arg->resp), - .outsize = sizeof(arg->req), - }, - .data.req = arg->req - }; - - ret = cros_ec_cmd_xfer_status(cros_ec, &buf.msg); + + ret = cros_ec_cmd(cros_ec, 1, EC_CMD_LED_CONTROL, + &arg->req, sizeof(arg->req), &arg->resp, sizeof(arg->resp)); if (ret < 0) return ret; - arg->resp = buf.data.resp; - return 0; } > > as in other cases: > > https://lore.kernel.org/linux-hardening/Z-a4meHAy-t58bcE@kspp/ > > -Gustavo > > > going on. We have the utility function cros_ec_cmd() which would be the > > nicer alternative. (Without having verified that it avoids the warning). > > While it is slightly more expensive, I don't think it matters. > > And if it does, the helper can be optimized. > > > > (The same goes for my other cros_ec drivers) > > > > > + > > > + ret = cros_ec_cmd_xfer_status(cros_ec, msg); > > > if (ret < 0) > > > return ret; > > > - arg->resp = buf.data.resp; > > > + arg->resp = *(struct ec_response_led_control *)msg->data; > > > return 0; > > > } Thomas
> My issue was with the general usage of DEFINE_RAW_FLEX(), the reply was > placed badly. For somebody not knowing this construct it's not clear > what is happening under the hood. > It's probably fine in a regular header file with some explanation, > but in a random driver it looks off. > > The following is what I had in mind. Now actually tested. OK, let's go with that :) https://lore.kernel.org/linux-hardening/Z-rKcgFjsyKvd58q@kspp/ Thanks! -- Gustavo
diff --git a/drivers/leds/leds-cros_ec.c b/drivers/leds/leds-cros_ec.c index 275522b81ea5..6eab0474f52d 100644 --- a/drivers/leds/leds-cros_ec.c +++ b/drivers/leds/leds-cros_ec.c @@ -66,24 +66,20 @@ static int cros_ec_led_send_cmd(struct cros_ec_device *cros_ec, union cros_ec_led_cmd_data *arg) { int ret; - struct { - struct cros_ec_command msg; - union cros_ec_led_cmd_data data; - } __packed buf = { - .msg = { - .version = 1, - .command = EC_CMD_LED_CONTROL, - .insize = sizeof(arg->resp), - .outsize = sizeof(arg->req), - }, - .data.req = arg->req - }; - - ret = cros_ec_cmd_xfer_status(cros_ec, &buf.msg); + DEFINE_RAW_FLEX(struct cros_ec_command, msg, data, + sizeof(union cros_ec_led_cmd_data)); + + msg->version = 1; + msg->command = EC_CMD_LED_CONTROL; + msg->insize = sizeof(arg->resp); + msg->outsize = sizeof(arg->req); + *(struct ec_params_led_control *)msg->data = arg->req; + + ret = cros_ec_cmd_xfer_status(cros_ec, msg); if (ret < 0) return ret; - arg->resp = buf.data.resp; + arg->resp = *(struct ec_response_led_control *)msg->data; return 0; }
-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/leds/leds-cros_ec.c:70:40: 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> --- drivers/leds/leds-cros_ec.c | 26 +++++++++++--------------- 1 file changed, 11 insertions(+), 15 deletions(-)