From 3c80d3794dac5b0f50132846113a120d881462ec Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 9 Mar 2020 10:57:22 -0500 Subject: dlm: user: Replace zero-length array with flexible-array member 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 Signed-off-by: David Teigland --- fs/dlm/user.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/dlm/user.c') diff --git a/fs/dlm/user.c b/fs/dlm/user.c index 5264bac75115..e5cefa90b1ce 100644 --- a/fs/dlm/user.c +++ b/fs/dlm/user.c @@ -46,7 +46,7 @@ struct dlm_lock_params32 { __u32 bastaddr; __u32 lksb; char lvb[DLM_USER_LVB_LEN]; - char name[0]; + char name[]; }; struct dlm_write_request32 { -- cgit v1.2.3