On Thu, May 21, 2020 at 01:32:35PM -0500, Gustavo A. R. Silva wrote:
> Hi all,
>
> Friendly ping: who can take this?
It is in the tree. Let me send out a git pull to Linus in a week or two.
Thanks!
>
> Thanks
> --
> Gustavo
>
> On Thu, May 07, 2020 at 01:55:44PM -0500, 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]
> >
> > sizeof(flexible-array-member) triggers a warning because flexible array
> > members have incomplete type[1]. There are some instances of code in
> > which the sizeof operator is being incorrectly/erroneously applied to
> > zero-length arrays and the result is zero. Such instances may be hiding
> > some bugs. So, this work (flexible-array member conversions) will also
> > help to get completely rid of those sorts of issues.
> >
> > 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 <[email protected]>
> > ---
> > drivers/firmware/iscsi_ibft.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/firmware/iscsi_ibft.c b/drivers/firmware/iscsi_ibft.c
> > index 96758b71a8db..7127a04bca19 100644
> > --- a/drivers/firmware/iscsi_ibft.c
> > +++ b/drivers/firmware/iscsi_ibft.c
> > @@ -104,7 +104,7 @@ struct ibft_control {
> > u16 tgt0_off;
> > u16 nic1_off;
> > u16 tgt1_off;
> > - u16 expansion[0];
> > + u16 expansion[];
> > } __attribute__((__packed__));
> >
> > struct ibft_initiator {
> >
