* [PATCH] USB: serial: ti_usb_3410_5052: Replace zero-length array with flexible-array member
@ 2020-02-11 23:24 Gustavo A. R. Silva
2020-02-12 7:59 ` Johan Hovold
0 siblings, 1 reply; 3+ messages in thread
From: Gustavo A. R. Silva @ 2020-02-11 23:24 UTC (permalink / raw)
To: Johan Hovold, Greg Kroah-Hartman
Cc: linux-usb, linux-kernel, Gustavo A. R. Silva
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertenly introduced[3] to the codebase from now on.
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
drivers/usb/serial/ti_usb_3410_5052.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/serial/ti_usb_3410_5052.c b/drivers/usb/serial/ti_usb_3410_5052.c
index dd0ad67aa71e..db3ab25d9228 100644
--- a/drivers/usb/serial/ti_usb_3410_5052.c
+++ b/drivers/usb/serial/ti_usb_3410_5052.c
@@ -219,7 +219,7 @@ struct ti_write_data_bytes {
u8 bDataCounter;
__be16 wBaseAddrHi;
__be16 wBaseAddrLo;
- u8 bData[0];
+ u8 bData[];
} __packed;
struct ti_read_data_request {
@@ -234,7 +234,7 @@ struct ti_read_data_bytes {
__u8 bCmdCode;
__u8 bModuleId;
__u8 bErrorCode;
- __u8 bData[0];
+ __u8 bData[];
} __packed;
/* Interrupt struct */
--
2.25.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] USB: serial: ti_usb_3410_5052: Replace zero-length array with flexible-array member
2020-02-11 23:24 [PATCH] USB: serial: ti_usb_3410_5052: Replace zero-length array with flexible-array member Gustavo A. R. Silva
@ 2020-02-12 7:59 ` Johan Hovold
2020-02-12 19:04 ` Gustavo A. R. Silva
0 siblings, 1 reply; 3+ messages in thread
From: Johan Hovold @ 2020-02-12 7:59 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Johan Hovold, Greg Kroah-Hartman, linux-usb, linux-kernel
On Tue, Feb 11, 2020 at 05:24:20PM -0600, Gustavo A. R. Silva wrote:
> The current codebase makes use of the zero-length array language
> extension to the C90 standard, but the preferred mechanism to declare
> variable-length types such as these ones is a flexible array member[1][2],
> introduced in C99:
>
> struct foo {
> int stuff;
> struct boo array[];
> };
>
> By making use of the mechanism above, we will get a compiler warning
> in case the flexible array does not occur last in the structure, which
> will help us prevent some kind of undefined behavior bugs from being
> inadvertenly introduced[3] to the codebase from now on.
>
> This issue was found with the help of Coccinelle.
Same here, the scripts may need to be updated as you missed a couple of
instances:
$ git grep '\[0\];' drivers/usb/serial
...
drivers/usb/serial/io_usbvend.h: __u8 Data[0]; // Data starts here
drivers/usb/serial/io_usbvend.h: __u8 Data[0]; // Download starts here
...
Could you replace these as well so that is done in one patch per
subsystem?
> [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
> [2] https://github.com/KSPP/linux/issues/21
> [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
> drivers/usb/serial/ti_usb_3410_5052.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/serial/ti_usb_3410_5052.c b/drivers/usb/serial/ti_usb_3410_5052.c
> index dd0ad67aa71e..db3ab25d9228 100644
> --- a/drivers/usb/serial/ti_usb_3410_5052.c
> +++ b/drivers/usb/serial/ti_usb_3410_5052.c
> @@ -219,7 +219,7 @@ struct ti_write_data_bytes {
> u8 bDataCounter;
> __be16 wBaseAddrHi;
> __be16 wBaseAddrLo;
> - u8 bData[0];
> + u8 bData[];
> } __packed;
>
> struct ti_read_data_request {
> @@ -234,7 +234,7 @@ struct ti_read_data_bytes {
> __u8 bCmdCode;
> __u8 bModuleId;
> __u8 bErrorCode;
> - __u8 bData[0];
> + __u8 bData[];
> } __packed;
>
> /* Interrupt struct */
Thanks,
Johan
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] USB: serial: ti_usb_3410_5052: Replace zero-length array with flexible-array member
2020-02-12 7:59 ` Johan Hovold
@ 2020-02-12 19:04 ` Gustavo A. R. Silva
0 siblings, 0 replies; 3+ messages in thread
From: Gustavo A. R. Silva @ 2020-02-12 19:04 UTC (permalink / raw)
To: Johan Hovold; +Cc: Greg Kroah-Hartman, linux-usb, linux-kernel
On 2/12/20 01:59, Johan Hovold wrote:
> On Tue, Feb 11, 2020 at 05:24:20PM -0600, Gustavo A. R. Silva wrote:
>> The current codebase makes use of the zero-length array language
>> extension to the C90 standard, but the preferred mechanism to declare
>> variable-length types such as these ones is a flexible array member[1][2],
>> introduced in C99:
>>
>> struct foo {
>> int stuff;
>> struct boo array[];
>> };
>>
>> By making use of the mechanism above, we will get a compiler warning
>> in case the flexible array does not occur last in the structure, which
>> will help us prevent some kind of undefined behavior bugs from being
>> inadvertenly introduced[3] to the codebase from now on.
>>
>> This issue was found with the help of Coccinelle.
>
> Same here, the scripts may need to be updated as you missed a couple of
> instances:
>
> $ git grep '\[0\];' drivers/usb/serial
> ...
> drivers/usb/serial/io_usbvend.h: __u8 Data[0]; // Data starts here
> drivers/usb/serial/io_usbvend.h: __u8 Data[0]; // Download starts here
> ...
>
> Could you replace these as well so that is done in one patch per
> subsystem?
>
Sure thing. I'll do that.
Thanks for the feedback.
--
Gustavo
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-02-11 23:24 [PATCH] USB: serial: ti_usb_3410_5052: Replace zero-length array with flexible-array member Gustavo A. R. Silva
2020-02-12 7:59 ` Johan Hovold
2020-02-12 19:04 ` Gustavo A. R. Silva
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