* [PATCH] crypto: s5p-sss - Replace zero-length array with flexible-array member
@ 2020-02-13 17:21 ` Gustavo A. R. Silva
2020-02-14 7:09 ` Kamil Konieczny
2020-02-22 1:43 ` Herbert Xu
0 siblings, 2 replies; 4+ messages in thread
From: Gustavo A. R. Silva @ 2020-02-13 17:21 UTC (permalink / raw)
To: Krzysztof Kozlowski, Vladimir Zapolskiy, Kamil Konieczny,
Herbert Xu, David S. Miller
Cc: linux-crypto, linux-samsung-soc, linux-kernel, Gustavo A. R. Silva
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>
---
drivers/crypto/s5p-sss.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/crypto/s5p-sss.c b/drivers/crypto/s5p-sss.c
index d66e20a2f54c..2a16800d2579 100644
--- a/drivers/crypto/s5p-sss.c
+++ b/drivers/crypto/s5p-sss.c
@@ -369,7 +369,7 @@ struct s5p_hash_reqctx {
bool error;
u32 bufcnt;
- u8 buffer[0];
+ u8 buffer[];
};
/**
--
2.25.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] crypto: s5p-sss - Replace zero-length array with flexible-array member
2020-02-13 17:21 ` [PATCH] crypto: s5p-sss - Replace zero-length array with flexible-array member Gustavo A. R. Silva
@ 2020-02-14 7:09 ` Kamil Konieczny
2020-02-14 8:22 ` Krzysztof Kozlowski
2020-02-22 1:43 ` Herbert Xu
1 sibling, 1 reply; 4+ messages in thread
From: Kamil Konieczny @ 2020-02-14 7:09 UTC (permalink / raw)
To: Gustavo A. R. Silva, Krzysztof Kozlowski, Vladimir Zapolskiy,
Herbert Xu, David S. Miller
Cc: linux-crypto, linux-samsung-soc, linux-kernel,
Bartlomiej Zolnierkiewicz, Marek Szyprowski
On 13.02.2020 18:21, 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://protect2.fireeye.com/url?k=7fbec6f4-22720d30-7fbf4dbb-0cc47a314e9a-2a4d03985644c7ed&u=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/crypto/s5p-sss.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/crypto/s5p-sss.c b/drivers/crypto/s5p-sss.c
> index d66e20a2f54c..2a16800d2579 100644
> --- a/drivers/crypto/s5p-sss.c
> +++ b/drivers/crypto/s5p-sss.c
> @@ -369,7 +369,7 @@ struct s5p_hash_reqctx {
> bool error;
>
> u32 bufcnt;
> - u8 buffer[0];
> + u8 buffer[];
> };
>
> /**
>
Looks good to me.
Acked-by: Kamil Konieczny <k.konieczny@samsung.com>
--
Best regards,
Kamil Konieczny
Samsung R&D Institute Poland
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] crypto: s5p-sss - Replace zero-length array with flexible-array member
2020-02-14 7:09 ` Kamil Konieczny
@ 2020-02-14 8:22 ` Krzysztof Kozlowski
0 siblings, 0 replies; 4+ messages in thread
From: Krzysztof Kozlowski @ 2020-02-14 8:22 UTC (permalink / raw)
To: Kamil Konieczny
Cc: Gustavo A. R. Silva, Vladimir Zapolskiy, Herbert Xu,
David S. Miller, linux-crypto, linux-samsung-soc, linux-kernel,
Bartlomiej Zolnierkiewicz, Marek Szyprowski
On Fri, 14 Feb 2020 at 08:09, Kamil Konieczny <k.konieczny@samsung.com> wrote:
>
> On 13.02.2020 18:21, 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://protect2.fireeye.com/url?k=7fbec6f4-22720d30-7fbf4dbb-0cc47a314e9a-2a4d03985644c7ed&u=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/crypto/s5p-sss.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/crypto/s5p-sss.c b/drivers/crypto/s5p-sss.c
> > index d66e20a2f54c..2a16800d2579 100644
> > --- a/drivers/crypto/s5p-sss.c
> > +++ b/drivers/crypto/s5p-sss.c
> > @@ -369,7 +369,7 @@ struct s5p_hash_reqctx {
> > bool error;
> >
> > u32 bufcnt;
> > - u8 buffer[0];
> > + u8 buffer[];
> > };
> >
> > /**
> >
>
> Looks good to me.
>
> Acked-by: Kamil Konieczny <k.konieczny@samsung.com>
Why not making it simple/obvious u8 *buffer? Or fixed length (BUFLEN length)?
Best regards,
Krzysztof
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] crypto: s5p-sss - Replace zero-length array with flexible-array member
2020-02-13 17:21 ` [PATCH] crypto: s5p-sss - Replace zero-length array with flexible-array member Gustavo A. R. Silva
2020-02-14 7:09 ` Kamil Konieczny
@ 2020-02-22 1:43 ` Herbert Xu
1 sibling, 0 replies; 4+ messages in thread
From: Herbert Xu @ 2020-02-22 1:43 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Krzysztof Kozlowski, Vladimir Zapolskiy, Kamil Konieczny,
David S. Miller, linux-crypto, linux-samsung-soc, linux-kernel
On Thu, Feb 13, 2020 at 11:21:30AM -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 <gustavo@embeddedor.com>
> ---
> drivers/crypto/s5p-sss.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
Patch applied. Thanks.
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-02-22 1:43 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
[not found] <CGME20200213180724eucas1p1bb96993e9d0300cddf348d5d442f43aa@eucas1p1.samsung.com>
2020-02-13 17:21 ` [PATCH] crypto: s5p-sss - Replace zero-length array with flexible-array member Gustavo A. R. Silva
2020-02-14 7:09 ` Kamil Konieczny
2020-02-14 8:22 ` Krzysztof Kozlowski
2020-02-22 1:43 ` Herbert Xu
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).