[packages/kernel/LINUX_3_18] - rel2; add CVE-2016-8655 fix (local root if having access to AF_PACKET)

[arekm]

commit 34e406c082ad3a905a35c2929917295dc10ac075
Author: Arkadiusz Miśkiewicz <arekm at maven.pl>
Date:   Wed Dec 7 10:43:08 2016 +0100

    - rel2; add CVE-2016-8655 fix (local root if having access to AF_PACKET)

 kernel-small_fixes.patch | 92 ++++++++++++++++++++++++++++++++++++++++++++++++
 kernel.spec              |  2 +-
 2 files changed, 93 insertions(+), 1 deletion(-)
---
diff --git a/kernel.spec b/kernel.spec
index 5be49d3..3bb4d17 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -70,7 +70,7 @@
 %define		have_pcmcia	0
 %endif
 
-%define		rel		1
+%define		rel		2
 %define		basever		3.18
 %define		postver		.45
 
diff --git a/kernel-small_fixes.patch b/kernel-small_fixes.patch
index 12c7335..3d121d1 100644
--- a/kernel-small_fixes.patch
+++ b/kernel-small_fixes.patch
@@ -62,3 +62,95 @@
  {
  	int err;
  
+From 84ac7260236a49c79eede91617700174c2c19b0c Mon Sep 17 00:00:00 2001
+From: Philip Pettersson <philip.pettersson at gmail.com>
+Date: Wed, 30 Nov 2016 14:55:36 -0800
+Subject: packet: fix race condition in packet_set_ring
+
+When packet_set_ring creates a ring buffer it will initialize a
+struct timer_list if the packet version is TPACKET_V3. This value
+can then be raced by a different thread calling setsockopt to
+set the version to TPACKET_V1 before packet_set_ring has finished.
+
+This leads to a use-after-free on a function pointer in the
+struct timer_list when the socket is closed as the previously
+initialized timer will not be deleted.
+
+The bug is fixed by taking lock_sock(sk) in packet_setsockopt when
+changing the packet version while also taking the lock at the start
+of packet_set_ring.
+
+Fixes: f6fb8f100b80 ("af-packet: TPACKET_V3 flexible buffer implementation.")
+Signed-off-by: Philip Pettersson <philip.pettersson at gmail.com>
+Signed-off-by: Eric Dumazet <edumazet at google.com>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ net/packet/af_packet.c | 18 ++++++++++++------
+ 1 file changed, 12 insertions(+), 6 deletions(-)
+
+diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
+index d2238b2..dd23323 100644
+--- a/net/packet/af_packet.c
++++ b/net/packet/af_packet.c
+@@ -3648,19 +3648,25 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
+ 
+ 		if (optlen != sizeof(val))
+ 			return -EINVAL;
+-		if (po->rx_ring.pg_vec || po->tx_ring.pg_vec)
+-			return -EBUSY;
+ 		if (copy_from_user(&val, optval, sizeof(val)))
+ 			return -EFAULT;
+ 		switch (val) {
+ 		case TPACKET_V1:
+ 		case TPACKET_V2:
+ 		case TPACKET_V3:
+-			po->tp_version = val;
+-			return 0;
++			break;
+ 		default:
+ 			return -EINVAL;
+ 		}
++		lock_sock(sk);
++		if (po->rx_ring.pg_vec || po->tx_ring.pg_vec) {
++			ret = -EBUSY;
++		} else {
++			po->tp_version = val;
++			ret = 0;
++		}
++		release_sock(sk);
++		return ret;
+ 	}
+ 	case PACKET_RESERVE:
+ 	{
+@@ -4164,6 +4170,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
+ 	/* Added to avoid minimal code churn */
+ 	struct tpacket_req *req = &req_u->req;
+ 
++	lock_sock(sk);
+ 	/* Opening a Tx-ring is NOT supported in TPACKET_V3 */
+ 	if (!closing && tx_ring && (po->tp_version > TPACKET_V2)) {
+ 		net_warn_ratelimited("Tx-ring is not supported.\n");
+@@ -4245,7 +4252,6 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
+ 			goto out;
+ 	}
+ 
+-	lock_sock(sk);
+ 
+ 	/* Detach socket from network */
+ 	spin_lock(&po->bind_lock);
+@@ -4294,11 +4300,11 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
+ 		if (!tx_ring)
+ 			prb_shutdown_retire_blk_timer(po, rb_queue);
+ 	}
+-	release_sock(sk);
+ 
+ 	if (pg_vec)
+ 		free_pg_vec(pg_vec, order, req->tp_block_nr);
+ out:
++	release_sock(sk);
+ 	return err;
+ }
+ 
+-- 
+cgit v0.12
+
================================================================

---- gitweb:

http://git.pld-linux.org/gitweb.cgi/packages/kernel.git/commitdiff/34e406c082ad3a905a35c2929917295dc10ac075