| Message ID | 20170104.132452.646592152519338774.davem@davemloft.net |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
Thanks > -----Original Message----- > From: David Miller [mailto:davem@davemloft.net] > Sent: Thursday, January 05, 2017 2:25 AM > To: cugyly@163.com > Cc: netdev@vger.kernel.org; YUAN Linyu > Subject: Re: [PATCH] scm: remove use CMSG{_COMPAT}_ALIGN(sizeof(struct > {compat_}cmsghdr)) > > From: yuan linyu <cugyly@163.com> > Date: Tue, 3 Jan 2017 20:42:17 +0800 > > > From: yuan linyu <Linyu.Yuan@alcatel-sbell.com.cn> > > > > sizeof(struct cmsghdr) and sizeof(struct compat_cmsghdr) already aligned. > > remove use CMSG_ALIGN(sizeof(struct cmsghdr)) and > > CMSG_COMPAT_ALIGN(sizeof(struct compat_cmsghdr)) keep code > consistent. > > > > Signed-off-by: yuan linyu <Linyu.Yuan@alcatel-sbell.com.cn> > > Applied, and I added the following commit which will make sure our > analysis is accurate. > > ==================== > [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 <davem@davemloft.net> > --- > net/compat.c | 3 +++ > net/socket.c | 2 ++ > 2 files changed, 5 insertions(+) > > diff --git a/net/compat.c b/net/compat.c > index 4e27dd1..ba3ac72 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 8487bf1..5f3b5a2 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) > -- > 2.4.11
==================== [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 <davem@davemloft.net> --- net/compat.c | 3 +++ net/socket.c | 2 ++ 2 files changed, 5 insertions(+) diff --git a/net/compat.c b/net/compat.c index 4e27dd1..ba3ac72 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 8487bf1..5f3b5a2 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)