From 1e6fc0b690191005a49468c296ad49d0caacacf1 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Thu, 9 Jun 2016 13:42:06 -0400 Subject: avoid padding gaps in struct sockaddr_storage compilers are free not to copy, or in some cases to clobber, padding bytes in a structure. while it's an aliasing violation, and thus undefined behavior, to copy or manipulate other sockaddr types using sockaddr_storage, it seems likely that traditional code attempts to do so, and the original intent of the sockaddr_storage structure was probably to allow such usage. in the interest of avoiding silent and potentially dangerous breakage, ensure that there are no actual padding bytes in sockaddr_storage by moving and adjusting the size of the __ss_padding member so that it fits exactly. this change also removes a silent assumption that the alignment of long is equal to its size. --- include/sys/socket.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/sys/socket.h b/include/sys/socket.h index 76fbde04..55e53d2a 100644 --- a/include/sys/socket.h +++ b/include/sys/socket.h @@ -306,8 +306,8 @@ struct sockaddr struct sockaddr_storage { sa_family_t ss_family; + char __ss_padding[128-sizeof(long)-sizeof(sa_family_t)]; unsigned long __ss_align; - char __ss_padding[128-2*sizeof(unsigned long)]; }; int socket (int, int, int); -- cgit v1.2.1