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USB: serial: ti_usb_3410_5052: Use struct_size() helper in ti_write_byte()

PATCH In review Gustavo A. R. Silva 3 participants 3 messages Jan 20, 2022 – Mar 3, 2022

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Gustavo A. R. Silva

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#0 lore raw

PATCH 1/1 USB: serial: ti_usb_3410_5052: Use struct_size() helper in ti_write_byte()

Make use of the struct_size() helper instead of an open-coded version, in order to avoid any potential type mistakes or integer overflows that, in the worst scenario, could lead to heap overflows.

Also, address the following sparse warnings:
drivers/usb/serial/ti_usb_3410_5052.c:1521:16: warning: using sizeof on a flexible structure

Link https://github.com/KSPP/linux/issues/174
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
 drivers/usb/serial/ti_usb_3410_5052.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
drivers/usb/serial/ti_usb_3410_5052.c +2 -2
index 18c0bd853392..03f98e61626f 100644
@@ -1512,13 +1512,13 @@ static int ti_write_byte(struct usb_serial_port *port,
 			 u8 mask, u8 byte)
 {
 	int status;
-	unsigned int size;
+	size_t size;
 	struct ti_write_data_bytes *data;
 
 	dev_dbg(&port->dev, "%s - addr 0x%08lX, mask 0x%02X, byte 0x%02X\n", __func__,
 		addr, mask, byte);
 
-	size = sizeof(struct ti_write_data_bytes) + 2;
+	size = struct_size(data, bData, 2);
 	data = kmalloc(size, GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
Signature · 1 line
2.27.0
Reviewed-by on v1 1/1
#1 lore raw
Quoted 9 lines · Gustavo A. R. Silva

Make use of the struct_size() helper instead of an open-coded version, in order to avoid any potential type mistakes or integer overflows that, in the worst scenario, could lead to heap overflows.

Also, address the following sparse warnings:
drivers/usb/serial/ti_usb_3410_5052.c:1521:16: warning: using sizeof on a flexible structure

Link https://github.com/KSPP/linux/issues/174
Signed-off-by Gustavo A. R. Silva <[email protected]>

Looks good.

Reviewed-by Kees Cook <[email protected]>
Signature · 1 line
Kees Cook
maintainer
#2 lore raw
In reply to Gustavo A. R. Silva
Quoted 3 lines · Gustavo A. R. Silva

Make use of the struct_size() helper instead of an open-coded version, in order to avoid any potential type mistakes or integer overflows that, in the worst scenario, could lead to heap overflows.

This boiler-plate motivation doesn't apply here since the "variable" size is in fact constant.

Quoted 2 lines

Also, address the following sparse warnings:
drivers/usb/serial/ti_usb_3410_5052.c:1521:16: warning: using sizeof on a flexible structure

And this bit is again bogus, since this off-by-default warning would still be there with this patch applied.

Quoted 13 lines
Link https://github.com/KSPP/linux/issues/174
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
 drivers/usb/serial/ti_usb_3410_5052.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
drivers/usb/serial/ti_usb_3410_5052.c +0 -0
index 18c0bd853392..03f98e61626f 100644
@@ -1512,13 +1512,13 @@ static int ti_write_byte(struct usb_serial_port *port,
 			 u8 mask, u8 byte)
 {

drivers/usb/serial/ti_usb_3410_5052.c static int ti_write_byte(struct usb_serial_port *port, · line 1521

Quoted 10 lines
drivers/usb/serial/ti_usb_3410_5052.c +2 -2
 	int status;
-	unsigned int size;
+	size_t size;
 	struct ti_write_data_bytes *data;
 
 	dev_dbg(&port->dev, "%s - addr 0x%08lX, mask 0x%02X, byte 0x%02X\n", __func__,
 		addr, mask, byte);
 
-	size = sizeof(struct ti_write_data_bytes) + 2;
+	size = struct_size(data, bData, 2);

I guess the change itself is fine otherwise and could be motivated as documenting the constant.

At least as long as the compiler is smart enough to not generate any additional code for this, there wouldn't be any downsides.

drivers/usb/serial/ti_usb_3410_5052.c static int ti_write_byte(struct usb_serial_port *port, · line 1524

Quoted 3 lines
drivers/usb/serial/ti_usb_3410_5052.c +0 -0
 	data = kmalloc(size, GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

Johan