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@xxxxxxxxxx>
---
drivers/crypto/chelsio/chcr_crypto.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/crypto/chelsio/chcr_crypto.h b/drivers/crypto/chelsio/chcr_crypto.h
index 542bebae001f..1cc522a07aac 100644
--- a/drivers/crypto/chelsio/chcr_crypto.h
+++ b/drivers/crypto/chelsio/chcr_crypto.h
@@ -223,7 +223,7 @@ struct chcr_authenc_ctx {
struct __aead_ctx {
struct chcr_gcm_ctx gcm[0];
- struct chcr_authenc_ctx authenc[0];
+ struct chcr_authenc_ctx authenc[];
};
struct chcr_aead_ctx {
@@ -235,7 +235,7 @@ struct chcr_aead_ctx {
u8 nonce[4];
u16 hmac_ctrl;
u16 mayverify;
- struct __aead_ctx ctx[0];
+ struct __aead_ctx ctx[];
};
struct hmac_ctx {
@@ -247,7 +247,7 @@ struct hmac_ctx {
struct __crypto_ctx {
struct hmac_ctx hmacctx[0];
struct ablk_ctx ablkctx[0];
- struct chcr_aead_ctx aeadctx[0];
+ struct chcr_aead_ctx aeadctx[];
};
struct chcr_context {
@@ -257,7 +257,7 @@ struct chcr_context {
unsigned int ntxq;
unsigned int nrxq;
struct completion cbc_aes_aio_done;
- struct __crypto_ctx crypto_ctx[0];
+ struct __crypto_ctx crypto_ctx[];
};
struct chcr_hctx_per_wr {
