Messages in this thread | | | Date | Tue, 23 Jun 2020 09:46:56 -0400 | From | Konrad Rzeszutek Wilk <> | Subject | Re: [PATCH] ibft: Replace zero-length array with flexible-array |
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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 <gustavoars@kernel.org> > > --- > > 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 { > >
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