On Mon, Feb 24, 2020 at 10:21:00AM -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
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 <redacted>
---
 drivers/crypto/caam/caamalg.c              | 2 +-
 drivers/crypto/caam/caamalg_qi.c           | 4 ++--
 drivers/crypto/caam/caamalg_qi2.h          | 6 +++---
 drivers/crypto/caam/caamhash.c             | 2 +-
 drivers/crypto/cavium/nitrox/nitrox_main.c | 2 +-
 drivers/crypto/chelsio/chcr_core.h         | 2 +-
 drivers/crypto/mediatek/mtk-sha.c          | 2 +-
 drivers/crypto/nx/nx.h                     | 2 +-
 drivers/crypto/omap-sham.c                 | 4 ++--
 include/crypto/if_alg.h                    | 2 +-
 10 files changed, 14 insertions(+), 14 deletions(-)

Patch applied.  Thanks.
-- 
Email: Herbert Xu [off-list ref]
Home Page: http://gondor.apana.org.au/~herbert/
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