| Message ID | 20200211211010.GA32239@embeddedor (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 57c45d4d8a9d78c962e9ddfc4fb2d3210f34f966 |
| Headers | show |
| Series | misc: vexpress: Replace zero-length array with flexible-array member | expand |
On Tue, Feb 11, 2020 at 03:10:10PM -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") > Applied for v5.7 -- Regards, Sudeep
diff --git a/drivers/misc/vexpress-syscfg.c b/drivers/misc/vexpress-syscfg.c index a3c6c773d9dc..5eb51f2be8f0 100644 --- a/drivers/misc/vexpress-syscfg.c +++ b/drivers/misc/vexpress-syscfg.c @@ -49,7 +49,7 @@ struct vexpress_syscfg_func { struct vexpress_syscfg *syscfg; struct regmap *regmap; int num_templates; - u32 template[0]; /* Keep it last! */ + u32 template[]; /* Keep it last! */ };
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/misc/vexpress-syscfg.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)