| Message ID | 20200211232420.GA22388@embeddedor (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | USB: serial: ti_usb_3410_5052: Replace zero-length array with flexible-array member | expand |
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
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
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 */
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(-)