| Message ID | 20200211234237.GA26971@embeddedor (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | hwmon: (ibmaem) Replace zero-length array with flexible-array member | expand |
On Tue, Feb 11, 2020 at 05:42:37PM -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 to hwmon-next. Thanks, Guenter > --- > drivers/hwmon/ibmaem.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/hwmon/ibmaem.c b/drivers/hwmon/ibmaem.c > index db63c1295cb2..fb052c2d9c34 100644 > --- a/drivers/hwmon/ibmaem.c > +++ b/drivers/hwmon/ibmaem.c > @@ -232,7 +232,7 @@ struct aem_read_sensor_req { > > struct aem_read_sensor_resp { > struct aem_iana_id id; > - u8 bytes[0]; > + u8 bytes[]; > } __packed; > > /* Data structures to talk to the IPMI layer */
diff --git a/drivers/hwmon/ibmaem.c b/drivers/hwmon/ibmaem.c index db63c1295cb2..fb052c2d9c34 100644 --- a/drivers/hwmon/ibmaem.c +++ b/drivers/hwmon/ibmaem.c @@ -232,7 +232,7 @@ struct aem_read_sensor_req { struct aem_read_sensor_resp { struct aem_iana_id id; - u8 bytes[0]; + u8 bytes[]; } __packed; /* Data structures to talk to the IPMI layer */
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/hwmon/ibmaem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)