From: Vincent <bernat@luffy.cx>
Date: Sat, 6 Mar 2010 08:53:40 +0000 (+0100)
Subject: Avoid dereferencing a type-punned pointer.
X-Git-Tag: 0.5.0~15
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=72c00381999c613115c23bbf080a8a18c5a7e691;p=thirdparty%2Flldpd.git

Avoid dereferencing a type-punned pointer.

When passing a file descriptor, we were dereferencing a unsigned char
pointer. This breaks strict-aliasing rules in C99. Moreover, we should
care about the alignment (even if in this case, this is aligned
because the previous member of the struct is an int). Therefore, we
use memcpy instead.
---

diff --git a/src/privsep_fdpass.c b/src/privsep_fdpass.c
index 7235dfb8..4a1a3140 100644
--- a/src/privsep_fdpass.c
+++ b/src/privsep_fdpass.c
@@ -68,7 +68,7 @@ send_fd(int sock, int fd)
 		cmsg->cmsg_len = CMSG_LEN(sizeof(int));
 		cmsg->cmsg_level = SOL_SOCKET;
 		cmsg->cmsg_type = SCM_RIGHTS;
-		*(int *)CMSG_DATA(cmsg) = fd;
+		memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));
 	} else {
 		result = errno;
 	}
@@ -121,7 +121,7 @@ receive_fd(int sock)
 		if (cmsg->cmsg_type != SCM_RIGHTS)
 			LLOG_WARNX("expected type %d got %d",
 			    SCM_RIGHTS, cmsg->cmsg_type);
-		fd = (*(int *)CMSG_DATA(cmsg));
+		memcpy(&fd, CMSG_DATA(cmsg), sizeof(int));
 		return fd;
 	} else {
 		errno = result;