Commit ac4340fc authored Jan 04, 2017 by David S. Miller

net: Assert at build time the assumptions we make about the CMSG header.



It must always be the case that CMSG_ALIGN(sizeof(hdr)) == sizeof(hdr).

Otherwise there are missing adjustments in the various calculations
that parse and build these things.

Signed-off-by: David S. Miller <davem@davemloft.net>

parent 1ff8cebf

net/compat.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -130,6 +130,9 @@ int cmsghdr_from_user_compat_to_kern(struct msghdr kmsg, struct sock sk,
		__kernel_size_t kcmlen, tmp;
		int err = -EFAULT;

		BUILD_BUG_ON(sizeof(struct compat_cmsghdr) !=
		CMSG_COMPAT_ALIGN(sizeof(struct compat_cmsghdr)));

		kcmlen = 0;
		kcmsg_base = kcmsg = (struct cmsghdr *)stackbuf;
		ucmsg = CMSG_COMPAT_FIRSTHDR(kmsg);

net/socket.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1948,6 +1948,8 @@ static int ___sys_sendmsg(struct socket sock, struct user_msghdr __user msg,
		ctl_buf = msg_sys->msg_control;
		ctl_len = msg_sys->msg_controllen;
		} else if (ctl_len) {
		BUILD_BUG_ON(sizeof(struct cmsghdr) !=
		CMSG_ALIGN(sizeof(struct cmsghdr)));
		if (ctl_len > sizeof(ctl)) {
		ctl_buf = sock_kmalloc(sock->sk, ctl_len, GFP_KERNEL);
		if (ctl_buf == NULL)