From 5a8a076506af03f83f83d80412a7c0b06b687ee1 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 24 Feb 2020 10:21:00 -0600 Subject: crypto: Replace zero-length array with flexible-array member MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Horia Geantă Signed-off-by: Herbert Xu --- drivers/crypto/omap-sham.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/crypto/omap-sham.c') diff --git a/drivers/crypto/omap-sham.c b/drivers/crypto/omap-sham.c index 4f915a4ef5b0..e4072cd38585 100644 --- a/drivers/crypto/omap-sham.c +++ b/drivers/crypto/omap-sham.c @@ -159,7 +159,7 @@ struct omap_sham_reqctx { int sg_len; unsigned int total; /* total request */ - u8 buffer[0] OMAP_ALIGNED; + u8 buffer[] OMAP_ALIGNED; }; struct omap_sham_hmac_ctx { @@ -176,7 +176,7 @@ struct omap_sham_ctx { /* fallback stuff */ struct crypto_shash *fallback; - struct omap_sham_hmac_ctx base[0]; + struct omap_sham_hmac_ctx base[]; }; #define OMAP_SHAM_QUEUE_LENGTH 10 -- cgit v1.2.3