diff options
author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-03-19 18:07:37 -0500 |
---|---|---|
committer | Dan Williams <dan.j.williams@intel.com> | 2020-03-30 12:37:09 -0700 |
commit | 1e361632da12ac00cb86c25a857ba251fdf2de95 (patch) | |
tree | 2b38550d6351c356da58b3158c2f17c4a47dc926 /drivers | |
parent | 4b566406085bc1fd5b6ba309fae70e6f6d6fa94e (diff) | |
download | linux-1e361632da12ac00cb86c25a857ba251fdf2de95.tar.bz2 |
libnvdimm/label: Replace zero-length array with flexible-array member
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
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
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>
Link: https://lore.kernel.org/r/20200319230737.GA16452@embeddedor.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/nvdimm/label.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/nvdimm/label.h b/drivers/nvdimm/label.h index 4c7b775c2811..956b6d1bd8cc 100644 --- a/drivers/nvdimm/label.h +++ b/drivers/nvdimm/label.h @@ -62,7 +62,7 @@ struct nd_namespace_index { __le16 major; __le16 minor; __le64 checksum; - u8 free[0]; + u8 free[]; }; /** |