| Message ID | 20200211231045.GA13956@embeddedor (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | firmware: arm_scmi: driver: Replace zero-length array with flexible-array member | expand |
On Tue, Feb 11, 2020 at 05:10:45PM -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. > > [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> Applied these 3 patches [0][1][2] for v5.7 -- Regards, Sudeep [0]: https://lore.kernel.org/r/20200211231604.GA17274@embeddedor [1]: https://lore.kernel.org/r/20200211231252.GA14830@embeddedor [2]: https://lore.kernel.org/r/20200211231045.GA13956@embeddedor
On 2/20/20 11:18, Sudeep Holla wrote: >> >> [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> > > Applied these 3 patches [0][1][2] for v5.7 > Thanks, Sudeep. -- Gustavo
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c index 8f952f2f1a29..b40f71edc92d 100644 --- a/drivers/firmware/arm_scmi/driver.c +++ b/drivers/firmware/arm_scmi/driver.c @@ -148,7 +148,7 @@ struct scmi_shared_mem { #define SCMI_SHMEM_FLAG_INTR_ENABLED BIT(0) __le32 length; __le32 msg_header; - u8 msg_payload[0]; + u8 msg_payload[]; }; static const int scmi_linux_errmap[] = {
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/firmware/arm_scmi/driver.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)