[PATCH 0/3] Fix erroneous ioctl returns

[PATCH 0/3] Fix erroneous ioctl returns

[Dave Penkler]

Recent tests with timeouts > INT_MAX produced random error returns
with usbtmc_get_stb. This was caused by assigning the return value
of wait_event_interruptible_timeout to an int which overflowed to
negative values. Also return value on success was the remaining
number of jiffies instead of 0.

These patches fix all the cases where the return of
wait_event_interruptible_timeout was assigned to an int and
the case of the remaining jiffies return in usbtmc_get_stb.

Patch 1: Fixes usbtmc_get_stb 
Patch 2: Fixes usbtmc488_ioctl_wait_srq
Patch 3: Fixes usbtmc_generic_read

Dave Penkler (3):
  usb: usbtmc: Fix erroneous get_stb ioctl error returns
  usb: usbtmc: Fix erroneous wait_srq ioctl return
  usb: usbtmc: Fix erroneous generic_read ioctl return

 drivers/usb/class/usbtmc.c | 53 ++++++++++++++++++++++----------------
 1 file changed, 31 insertions(+), 22 deletions(-)

-- 
2.49.0

[PATCH 1/3] usb: usbtmc: Fix erroneous get_stb ioctl error returns

[Dave Penkler]

wait_event_interruptible_timeout returns a long
The return was being assigned to an int causing an integer overflow when
the remaining jiffies > INT_MAX resulting in random error returns.

Use a long return value and convert to int ioctl return only on error.

On success the ioctl was returning the transfer length of the
usb_control_msg which has no meaning for the user.
Return 0 on success.

Reported-by: Michael Katzmann <vk2bea@gmail.com>
Fixes: dbf3e7f654c0 ("Implement an ioctl to support the USMTMC-USB488 READ_STATUS_BYTE operation.")
Signed-off-by: Dave Penkler <dpenkler@gmail.com>
---
 drivers/usb/class/usbtmc.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index 34e46ef308ab..e24277fef54a 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -482,6 +482,7 @@ static int usbtmc_get_stb(struct usbtmc_file_data *file_data, __u8 *stb)
 	u8 *buffer;
 	u8 tag;
 	int rv;
+	long wait_rv;
 
 	dev_dbg(dev, "Enter ioctl_read_stb iin_ep_present: %d\n",
 		data->iin_ep_present);
@@ -511,16 +512,17 @@ static int usbtmc_get_stb(struct usbtmc_file_data *file_data, __u8 *stb)
 	}
 
 	if (data->iin_ep_present) {
-		rv = wait_event_interruptible_timeout(
+		wait_rv = wait_event_interruptible_timeout(
 			data->waitq,
 			atomic_read(&data->iin_data_valid) != 0,
 			file_data->timeout);
-		if (rv < 0) {
-			dev_dbg(dev, "wait interrupted %d\n", rv);
+		if (wait_rv < 0) {
+			dev_dbg(dev, "wait interrupted %ld\n", wait_rv);
+			rv = wait_rv;
 			goto exit;
 		}
 
-		if (rv == 0) {
+		if (wait_rv == 0) {
 			dev_dbg(dev, "wait timed out\n");
 			rv = -ETIMEDOUT;
 			goto exit;
@@ -539,6 +541,8 @@ static int usbtmc_get_stb(struct usbtmc_file_data *file_data, __u8 *stb)
 
 	dev_dbg(dev, "stb:0x%02x received %d\n", (unsigned int)*stb, rv);
 
+	rv = 0;
+
  exit:
 	/* bump interrupt bTag */
 	data->iin_bTag += 1;
-- 
2.49.0

[PATCH 2/3] usb: usbtmc: Fix erroneous wait_srq ioctl return

[Dave Penkler]

wait_event_interruptible_timeout returns a long
The return was being assigned to an int causing an integer overflow when
the remaining jiffies > INT_MAX resulting in random error returns.

Use a long return value,  converting to the int ioctl return only on
error.

Fixes: 739240a9f6ac ("usb: usbtmc: Add ioctl USBTMC488_IOCTL_WAIT_SRQ")
Signed-off-by: Dave Penkler <dpenkler@gmail.com>
---
 drivers/usb/class/usbtmc.c | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index e24277fef54a..b3ca89b0dab7 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -606,9 +606,9 @@ static int usbtmc488_ioctl_wait_srq(struct usbtmc_file_data *file_data,
 {
 	struct usbtmc_device_data *data = file_data->data;
 	struct device *dev = &data->intf->dev;
-	int rv;
 	u32 timeout;
 	unsigned long expire;
+	long wait_rv;
 
 	if (!data->iin_ep_present) {
 		dev_dbg(dev, "no interrupt endpoint present\n");
@@ -622,25 +622,24 @@ static int usbtmc488_ioctl_wait_srq(struct usbtmc_file_data *file_data,
 
 	mutex_unlock(&data->io_mutex);
 
-	rv = wait_event_interruptible_timeout(
-			data->waitq,
-			atomic_read(&file_data->srq_asserted) != 0 ||
-			atomic_read(&file_data->closing),
-			expire);
+	wait_rv = wait_event_interruptible_timeout(
+		data->waitq,
+		atomic_read(&file_data->srq_asserted) != 0 ||
+		atomic_read(&file_data->closing),
+		expire);
 
 	mutex_lock(&data->io_mutex);
 
 	/* Note! disconnect or close could be called in the meantime */
 	if (atomic_read(&file_data->closing) || data->zombie)
-		rv = -ENODEV;
+		return -ENODEV;
 
-	if (rv < 0) {
-		/* dev can be invalid now! */
-		pr_debug("%s - wait interrupted %d\n", __func__, rv);
-		return rv;
+	if (wait_rv < 0) {
+		dev_dbg(dev, "%s - wait interrupted %ld\n", __func__, wait_rv);
+		return wait_rv;
 	}
 
-	if (rv == 0) {
+	if (wait_rv == 0) {
 		dev_dbg(dev, "%s - wait timed out\n", __func__);
 		return -ETIMEDOUT;
 	}
-- 
2.49.0

[PATCH 3/3] usb: usbtmc: Fix erroneous generic_read ioctl return

[Dave Penkler]

wait_event_interruptible_timeout returns a long
The return value was being assigned to an int causing an integer overflow
when the remaining jiffies > INT_MAX which resulted in random error
returns.

Use a long return value, converting to the int ioctl return only on error.

Fixes: bb99794a4792 ("usb: usbtmc: Add ioctl for vendor specific read")
Signed-off-by: Dave Penkler <dpenkler@gmail.com>
---
 drivers/usb/class/usbtmc.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index b3ca89b0dab7..025a7aa795e3 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -833,6 +833,7 @@ static ssize_t usbtmc_generic_read(struct usbtmc_file_data *file_data,
 	unsigned long expire;
 	int bufcount = 1;
 	int again = 0;
+	long wait_rv;
 
 	/* mutex already locked */
 
@@ -945,19 +946,24 @@ static ssize_t usbtmc_generic_read(struct usbtmc_file_data *file_data,
 		if (!(flags & USBTMC_FLAG_ASYNC)) {
 			dev_dbg(dev, "%s: before wait time %lu\n",
 				__func__, expire);
-			retval = wait_event_interruptible_timeout(
+			wait_rv = wait_event_interruptible_timeout(
 				file_data->wait_bulk_in,
 				usbtmc_do_transfer(file_data),
 				expire);
 
-			dev_dbg(dev, "%s: wait returned %d\n",
-				__func__, retval);
+			dev_dbg(dev, "%s: wait returned %ld\n",
+				__func__, wait_rv);
+
+			if (wait_rv < 0) {
+				retval = wait_rv;
+				goto error;
+			}
 
-			if (retval <= 0) {
-				if (retval == 0)
-					retval = -ETIMEDOUT;
+			if (wait_rv == 0) {
+				retval = -ETIMEDOUT;
 				goto error;
 			}
+
 		}
 
 		urb = usb_get_from_anchor(&file_data->in_anchor);
-- 
2.49.0

Re: [PATCH 1/3] usb: usbtmc: Fix erroneous get_stb ioctl error returns

[Greg KH]

On Sat, Apr 26, 2025 at 09:12:20PM +0200, Dave Penkler wrote:
> wait_event_interruptible_timeout returns a long
> The return was being assigned to an int causing an integer overflow when
> the remaining jiffies > INT_MAX resulting in random error returns.
> 
> Use a long return value and convert to int ioctl return only on error.
> 
> On success the ioctl was returning the transfer length of the
> usb_control_msg which has no meaning for the user.
> Return 0 on success.
> 
> Reported-by: Michael Katzmann <vk2bea@gmail.com>
> Fixes: dbf3e7f654c0 ("Implement an ioctl to support the USMTMC-USB488 READ_STATUS_BYTE operation.")
> Signed-off-by: Dave Penkler <dpenkler@gmail.com>
> ---
>  drivers/usb/class/usbtmc.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
> index 34e46ef308ab..e24277fef54a 100644
> --- a/drivers/usb/class/usbtmc.c
> +++ b/drivers/usb/class/usbtmc.c
> @@ -482,6 +482,7 @@ static int usbtmc_get_stb(struct usbtmc_file_data *file_data, __u8 *stb)
>  	u8 *buffer;
>  	u8 tag;
>  	int rv;
> +	long wait_rv;
>  
>  	dev_dbg(dev, "Enter ioctl_read_stb iin_ep_present: %d\n",
>  		data->iin_ep_present);
> @@ -511,16 +512,17 @@ static int usbtmc_get_stb(struct usbtmc_file_data *file_data, __u8 *stb)
>  	}
>  
>  	if (data->iin_ep_present) {
> -		rv = wait_event_interruptible_timeout(
> +		wait_rv = wait_event_interruptible_timeout(
>  			data->waitq,
>  			atomic_read(&data->iin_data_valid) != 0,
>  			file_data->timeout);
> -		if (rv < 0) {
> -			dev_dbg(dev, "wait interrupted %d\n", rv);
> +		if (wait_rv < 0) {
> +			dev_dbg(dev, "wait interrupted %ld\n", wait_rv);
> +			rv = wait_rv;
>  			goto exit;
>  		}
>  
> -		if (rv == 0) {
> +		if (wait_rv == 0) {
>  			dev_dbg(dev, "wait timed out\n");
>  			rv = -ETIMEDOUT;
>  			goto exit;
> @@ -539,6 +541,8 @@ static int usbtmc_get_stb(struct usbtmc_file_data *file_data, __u8 *stb)
>  
>  	dev_dbg(dev, "stb:0x%02x received %d\n", (unsigned int)*stb, rv);
>  
> +	rv = 0;
> +
>   exit:
>  	/* bump interrupt bTag */
>  	data->iin_bTag += 1;
> -- 
> 2.49.0
> 
> 

Hi,

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