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 --- include/crypto/if_alg.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/crypto') diff --git a/include/crypto/if_alg.h b/include/crypto/if_alg.h index 24cfa96f98ea..56527c85d122 100644 --- a/include/crypto/if_alg.h +++ b/include/crypto/if_alg.h @@ -66,7 +66,7 @@ struct af_alg_sgl { struct af_alg_tsgl { struct list_head list; unsigned int cur; /* Last processed SG entry */ - struct scatterlist sg[0]; /* Array of SGs forming the SGL */ + struct scatterlist sg[]; /* Array of SGs forming the SGL */ }; #define MAX_SGL_ENTS ((4096 - sizeof(struct af_alg_tsgl)) / \ -- cgit v1.2.3-59-g8ed1b