From ac4340fc3ce0e0b1cb627b05d6dcbd473544d7b3 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Wed, 4 Jan 2017 13:24:19 -0500 Subject: [PATCH] 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 --- net/compat.c | 3 +++ net/socket.c | 2 ++ 2 files changed, 5 insertions(+) diff --git a/net/compat.c b/net/compat.c index 4e27dd1cd3a6..ba3ac722714d 100644 --- a/net/compat.c +++ b/net/compat.c @@ -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); diff --git a/net/socket.c b/net/socket.c index 8487bf136e5c..5f3b5a2c4f37 100644 --- a/net/socket.c +++ b/net/socket.c @@ -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) -- 2.39.5