From 652913cd9474946bcb29271602bacfd98f46ad0b Mon Sep 17 00:00:00 2001 From: Adam Jackson Date: Wed, 13 Dec 2017 14:53:56 -0500 Subject: [PATCH] os: Fix a type error in the IPv6 XDMCP code MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Building with strict-aliasing rightly chirps here: ../os/xdmcp.c: In function ‘XdmcpRegisterConnection’: ../os/xdmcp.c:489:31: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing] &((struct sockaddr_in6 *) &address)->sin6_addr.s6_addr[12]; ^~~~~~~~~~~~ We have "const char *address", so &address here is a char ** (i.e., it points to the slot on the stack containing the pointer to the character array passed in as an argument). Casting that to a struct sockaddr_in6 * is wrong, because it means that area of the stack will be reinterpreted as a struct sockaddr_in6. Instead, cast address, not &address. Signed-off-by: Adam Jackson --- os/xdmcp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/os/xdmcp.c b/os/xdmcp.c index 7aeb393e6..d8c81fbf8 100644 --- a/os/xdmcp.c +++ b/os/xdmcp.c @@ -486,7 +486,7 @@ XdmcpRegisterConnection(int type, const char *address, int addrlen) IN6_IS_ADDR_V4MAPPED((const struct in6_addr *) address)) { fromAddr = &((struct sockaddr_in *) &FromAddress)->sin_addr; regAddr = - &((struct sockaddr_in6 *) &address)->sin6_addr.s6_addr[12]; + &((struct sockaddr_in6 *) address)->sin6_addr.s6_addr[12]; regAddrlen = sizeof(struct in_addr); } }