Patch "net: add validation for the socket syscall protocol argument" has been added to the 4.1-stable tree

This is a note to let you know that I've just added the patch titled

net: add validation for the socket syscall protocol argument

to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
net-add-validation-for-the-socket-syscall-protocol-argument.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Hannes Frederic Sowa <[email protected]>
Date: Mon, 14 Dec 2015 22:03:39 +0100
Subject: net: add validation for the socket syscall protocol argument
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From: Hannes Frederic Sowa <[email protected]>

[ Upstream commit 79462ad02e861803b3840cc782248c7359451cd9 ]

郭永刚 reported that one could simply crash the kernel as root by using a simple program:

	int socket_fd;
	struct sockaddr_in addr;
	addr.sin_port = 0;
	addr.sin_addr.s_addr = INADDR_ANY;
	addr.sin_family = 10;

	socket_fd = socket(10,3,0x40000000);
	connect(socket_fd , &addr,16);

AF_INET, AF_INET6 sockets actually only support 8-bit protocol identifiers. inet_sock's skc_protocol field thus is sized accordingly, thus larger protocol identifiers simply cut off the higher bits and store a zero in the protocol fields.

This could lead to e.g. NULL function pointer because as a result of the cut off inet_num is zero and we call down to inet_autobind, which is NULL for raw sockets.

kernel: Call Trace:
kernel:  [<ffffffff816db90e>] ? inet_autobind+0x2e/0x70
kernel:  [<ffffffff816db9a4>] inet_dgram_connect+0x54/0x80
kernel:  [<ffffffff81645069>] SYSC_connect+0xd9/0x110
kernel:  [<ffffffff810ac51b>] ? ptrace_notify+0x5b/0x80
kernel:  [<ffffffff810236d8>] ? syscall_trace_enter_phase2+0x108/0x200
kernel:  [<ffffffff81645e0e>] SyS_connect+0xe/0x10
kernel:  [<ffffffff81779515>] tracesys_phase2+0x84/0x89

I found no particular commit which introduced this problem.

CVE: CVE-2015-8543

---
 include/net/sock.h     |    1 +
 net/ax25/af_ax25.c     |    3 +++
 net/decnet/af_decnet.c |    3 +++
 net/ipv4/af_inet.c     |    3 +++
 net/ipv6/af_inet6.c    |    3 +++
 net/irda/af_irda.c     |    3 +++
 6 files changed, 16 insertions(+)

@@ -386,6 +386,7 @@ struct sock {
 				sk_no_check_rx : 1,
 				sk_userlocks : 4,
 				sk_protocol  : 8,
+#define SK_PROTOCOL_MAX U8_MAX
 				sk_type      : 16;
 	kmemcheck_bitfield_end(flags);
 	int			sk_wmem_queued;

@@ -806,6 +806,9 @@ static int ax25_create(struct net *net,
 	struct sock *sk;
 	ax25_cb *ax25;
 
+	if (protocol < 0 || protocol > SK_PROTOCOL_MAX)
+		return -EINVAL;
+
 	if (!net_eq(net, &init_net))
 		return -EAFNOSUPPORT;
 

@@ -678,6 +678,9 @@ static int dn_create(struct net *net, st
 {
 	struct sock *sk;
 
+	if (protocol < 0 || protocol > SK_PROTOCOL_MAX)
+		return -EINVAL;
+
 	if (!net_eq(net, &init_net))
 		return -EAFNOSUPPORT;
 

@@ -259,6 +259,9 @@ static int inet_create(struct net *net,
 	int try_loading_module = 0;
 	int err;
 
+	if (protocol < 0 || protocol >= IPPROTO_MAX)
+		return -EINVAL;
+
 	sock->state = SS_UNCONNECTED;
 
 	/* Look for the requested type/protocol pair. */

@@ -109,6 +109,9 @@ static int inet6_create(struct net *net,
 	int try_loading_module = 0;
 	int err;
 
+	if (protocol < 0 || protocol >= IPPROTO_MAX)
+		return -EINVAL;
+
 	/* Look for the requested type/protocol pair. */
 lookup_protocol:
 	err = -ESOCKTNOSUPPORT;

@@ -1086,6 +1086,9 @@ static int irda_create(struct net *net,
 	struct sock *sk;
 	struct irda_sock *self;
 
+	if (protocol < 0 || protocol > SK_PROTOCOL_MAX)
+		return -EINVAL;
+
 	if (net != &init_net)
 		return -EAFNOSUPPORT;
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/ipv6-automatically-enable-stable-privacy-mode-if-stable_secret-set.patch queue-4.1/af_unix-revert-lock_interruptible-in-stream-receive-code.patch queue-4.1/fou-clean-up-socket-with-kfree_rcu.patch queue-4.1/ipv6-keep-existing-flags-when-setting-ifa_f_optimistic.patch queue-4.1/net-add-validation-for-the-socket-syscall-protocol-argument.patch