netdev - [PATCH v3] net: don't return uninitialized addresses on concurrent socket shutdown

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sat, 16 Nov 2013 20:19:16 +0100
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	mpb <mpb.mail@...il.com>, netdev@...r.kernel.org,
	eric.dumazet@...il.com
Subject: [PATCH v3] net: don't return uninitialized addresses on concurrent socket shutdown

If a blocking read waits on a socket which gets concurrently shut down we
return 0 as error and so indicate success to the socket functions which
thus copies an uninitialized stack allocated address back to the user.

Fix this by introducing a new AF_INVALID sa_family marker and check if the
recvmsg function overwrote it. In case it was not overwritten, clear the
address with zeros (AF_UNSPEC) before returning it to the user. IMHO we
should only increase msg.msg_namelen (if we have to truncate the address),
so don't clear msg.msg_namelen.

This patch fixes the problem for recvfrom, recvmsg and recvmmsg.

Reported-by: mpb <mpb.mail@...il.com>
Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
---
 include/linux/socket.h | 2 ++
 net/socket.c           | 6 ++++++
 2 files changed, 8 insertions(+)

diff --git a/include/linux/socket.h b/include/linux/socket.h
index 445ef75..bdf9205 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -182,6 +182,8 @@ struct ucred {
 #define AF_VSOCK	40	/* vSockets			*/
 #define AF_MAX		41	/* For now.. */
 
+#define AF_INVALID	((__kernel_sa_family_t)(~0U))
+
 /* Protocol families, same as address families. */
 #define PF_UNSPEC	AF_UNSPEC
 #define PF_UNIX		AF_UNIX
diff --git a/net/socket.c b/net/socket.c
index c226ace..8361e15 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1834,6 +1834,7 @@ SYSCALL_DEFINE6(recvfrom, int, fd, void __user *, ubuf, size_t, size,
 	if (!sock)
 		goto out;
 
+	address.ss_family = AF_INVALID;
 	msg.msg_control = NULL;
 	msg.msg_controllen = 0;
 	msg.msg_iovlen = 1;
@@ -1847,6 +1848,8 @@ SYSCALL_DEFINE6(recvfrom, int, fd, void __user *, ubuf, size_t, size,
 	err = sock_recvmsg(sock, &msg, size, flags);
 
 	if (err >= 0 && addr != NULL) {
+		if (unlikely(address.ss_family == AF_INVALID))
+			memset(&address, 0, sizeof(address));
 		err2 = move_addr_to_user(&address,
 					 msg.msg_namelen, addr, addr_len);
 		if (err2 < 0)
@@ -2226,6 +2229,7 @@ static int ___sys_recvmsg(struct socket *sock, struct msghdr __user *msg,
 	 *      kernel msghdr to use the kernel address space)
 	 */
 
+	addr.ss_family = AF_INVALID;
 	uaddr = (__force void __user *)msg_sys->msg_name;
 	uaddr_len = COMPAT_NAMELEN(msg);
 	if (MSG_CMSG_COMPAT & flags) {
@@ -2248,6 +2252,8 @@ static int ___sys_recvmsg(struct socket *sock, struct msghdr __user *msg,
 	len = err;
 
 	if (uaddr != NULL) {
+		if (unlikely(addr.ss_family == AF_INVALID))
+			memset(&addr, 0, sizeof(addr));
 		err = move_addr_to_user(&addr,
 					msg_sys->msg_namelen, uaddr,
 					uaddr_len);
-- 
1.8.3.1

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html