From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Krzysztof Kozlowski <krzk@kernel.org>,
Vladimir Zapolskiy <vz@mleia.com>,
Kamil Konieczny <k.konieczny@samsung.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>
Cc: linux-crypto@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
linux-kernel@vger.kernel.org,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: [PATCH] crypto: s5p-sss - Replace zero-length array with flexible-array member
Date: Thu, 13 Feb 2020 11:21:30 -0600 [thread overview]
Message-ID: <20200213172130.GA13395@embeddedor> (raw)
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
next reply other threads:[~2020-02-13 17:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20200213180724eucas1p1bb96993e9d0300cddf348d5d442f43aa@eucas1p1.samsung.com>
2020-02-13 17:21 ` Gustavo A. R. Silva [this message]
2020-02-14 7:09 ` [PATCH] crypto: s5p-sss - Replace zero-length array with flexible-array member Kamil Konieczny
2020-02-14 8:22 ` Krzysztof Kozlowski
2020-02-22 1:43 ` Herbert Xu
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