[Cocci] [PATCH v2 net] nfp: cast sizeof() to int when comparing with error code

[Joe Perches]

sizeof() will return unsigned value so in the error check
negative error code will be always larger than sizeof().

This looks like a general class of error in the kernel
where a signed result that could be returning a -errno
is tested against < or <= sizeof()

A couple examples:

drivers/input/mouse/elan_i2c_smbus.c:

len = i2c_smbus_read_block_data(client,
ETP_SMBUS_IAP_PASSWORD_READ,
val);
if (len < sizeof(u16)) {

i2c_smbus_read_block_data can return a negative errno


net/smc/smc_clc.c:

len = kernel_sendmsg(smc->clcsock, &msg, &vec, 1,
sizeof(struct smc_clc_msg_decline));
if (len < sizeof(struct smc_clc_msg_decline))

where kernel_sendmsg can return a negative errno

There are probably others, I didn't look hard.

Perhaps a cocci script to find these could be generated?

[Julia Lawall]

Post by Joe Perches

sizeof() will return unsigned value so in the error check
negative error code will be always larger than sizeof().

This looks like a general class of error in the kernel
where a signed result that could be returning a -errno
is tested against < or <= sizeof()
len = i2c_smbus_read_block_data(client,
ETP_SMBUS_IAP_PASSWORD_READ,
val);
if (len < sizeof(u16)) {
i2c_smbus_read_block_data can return a negative errno
len = kernel_sendmsg(smc->clcsock, &msg, &vec, 1,
sizeof(struct smc_clc_msg_decline));
if (len < sizeof(struct smc_clc_msg_decline))
where kernel_sendmsg can return a negative errno
There are probably others, I didn't look hard.
Perhaps a cocci script to find these could be generated?

Currently there is a rule for comparison of unsigneds to 0. It would be
reasonable to extend it for sizes. I will see what it gives.

julia

[Julia Lawall]

Post by Joe Perches

sizeof() will return unsigned value so in the error check
negative error code will be always larger than sizeof().

This looks like a general class of error in the kernel
where a signed result that could be returning a -errno
is tested against < or <= sizeof()
len = i2c_smbus_read_block_data(client,
ETP_SMBUS_IAP_PASSWORD_READ,
val);
if (len < sizeof(u16)) {
i2c_smbus_read_block_data can return a negative errno
len = kernel_sendmsg(smc->clcsock, &msg, &vec, 1,
sizeof(struct smc_clc_msg_decline));
if (len < sizeof(struct smc_clc_msg_decline))
where kernel_sendmsg can return a negative errno
There are probably others, I didn't look hard.
Perhaps a cocci script to find these could be generated?

Here's another one:

drivers/usb/serial/ir-usb.c
@@ -126,13 +126,8 @@ irda_usb_find_class_desc(struct usb_seri
if (!desc)
return NULL;

- ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
- USB_REQ_CS_IRDA_GET_CLASS_DESC,
- USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
- 0, ifnum, desc, sizeof(*desc), 1000);

dev_dbg(&serial->dev->dev, "%s - ret=%d\n", __func__, ret);
- if (ret < sizeof(*desc)) {
dev_dbg(&serial->dev->dev,
"%s - class descriptor read %s (%d)\n", __func__,
(ret < 0) ? "failed" : "too short", ret);

There are other results, but I haven't checked all of them.

julia

[cgxu519]

Post by Julia Lawall

Post by Joe Perches

sizeof() will return unsigned value so in the error check
negative error code will be always larger than sizeof().

This looks like a general class of error in the kernel
where a signed result that could be returning a -errno
is tested against < or <= sizeof()
len = i2c_smbus_read_block_data(client,
ETP_SMBUS_IAP_PASSWORD_READ,
val);
if (len < sizeof(u16)) {
i2c_smbus_read_block_data can return a negative errno
len = kernel_sendmsg(smc->clcsock, &msg, &vec, 1,
sizeof(struct smc_clc_msg_decline));
if (len < sizeof(struct smc_clc_msg_decline))
where kernel_sendmsg can return a negative errno
There are probably others, I didn't look hard.
Perhaps a cocci script to find these could be generated?

drivers/usb/serial/ir-usb.c
@@ -126,13 +126,8 @@ irda_usb_find_class_desc(struct usb_seri
if (!desc)
return NULL;
- ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
- USB_REQ_CS_IRDA_GET_CLASS_DESC,
- USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
- 0, ifnum, desc, sizeof(*desc), 1000);
dev_dbg(&serial->dev->dev, "%s - ret=%d\n", __func__, ret);
- if (ret < sizeof(*desc)) {
dev_dbg(&serial->dev->dev,
"%s - class descriptor read %s (%d)\n", __func__,
(ret < 0) ? "failed" : "too short", ret);
There are other results, but I haven't checked all of them.

Hi Julia,

Thanks for your check. I posted a patch yesterday to fix three places in
usb subsystem
and the patch is just in queue now, so you can skip these places.

The detail of patch.
---

diff --git a/drivers/usb/serial/ir-usb.c b/drivers/usb/serial/ir-usb.c
index 24b06c7e5e2d..7643716b5299 100644
--- a/drivers/usb/serial/ir-usb.c
+++ b/drivers/usb/serial/ir-usb.c
@@ -132,7 +132,7 @@ irda_usb_find_class_desc(struct usb_serial *serial, unsigned int ifnum)
0, ifnum, desc, sizeof(*desc), 1000);

dev_dbg(&serial->dev->dev, "%s - ret=%d\n", __func__, ret);
- if (ret < sizeof(*desc)) {
+ if (ret < (int)sizeof(*desc)) {
dev_dbg(&serial->dev->dev,
"%s - class descriptor read %s (%d)\n", __func__,
(ret < 0) ? "failed" : "too short", ret);
diff --git a/drivers/usb/serial/quatech2.c b/drivers/usb/serial/quatech2.c
index 958e12e1e7c7..ff2322ea5e14 100644
--- a/drivers/usb/serial/quatech2.c
+++ b/drivers/usb/serial/quatech2.c
@@ -194,7 +194,7 @@ static inline int qt2_getregister(struct usb_device *dev,
ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
QT_SET_GET_REGISTER, 0xc0, reg,
uart, data, sizeof(*data), QT2_USB_TIMEOUT);
- if (ret < sizeof(*data)) {
+ if (ret < (int)sizeof(*data)) {
if (ret >= 0)
ret = -EIO;
}
diff --git a/drivers/usb/serial/ssu100.c b/drivers/usb/serial/ssu100.c
index 2083c267787b..0900b47b5f57 100644
--- a/drivers/usb/serial/ssu100.c
+++ b/drivers/usb/serial/ssu100.c
@@ -104,7 +104,7 @@ static inline int ssu100_getregister(struct usb_device *dev,
ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
QT_SET_GET_REGISTER, 0xc0, reg,
uart, data, sizeof(*data), 300);
- if (ret < sizeof(*data)) {
+ if (ret < (int)sizeof(*data)) {
if (ret >= 0)
ret = -EIO;
}
---




Thanks,
Chengguang.