From 50b1203d8c9c057558341cf02c0df66ba99a7877 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 9 Mar 2020 13:10:08 -0500 Subject: f2fs: xattr.h: 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 Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/xattr.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/f2fs') diff --git a/fs/f2fs/xattr.h b/fs/f2fs/xattr.h index 0153b4c9ef21..e471be77f8f0 100644 --- a/fs/f2fs/xattr.h +++ b/fs/f2fs/xattr.h @@ -49,7 +49,7 @@ struct f2fs_xattr_entry { __u8 e_name_index; __u8 e_name_len; __le16 e_value_size; /* size of attribute value */ - char e_name[0]; /* attribute name */ + char e_name[]; /* attribute name */ }; #define XATTR_HDR(ptr) ((struct f2fs_xattr_header *)(ptr)) -- cgit