fix CVE-2016-8655

diff --git a/CVE-2016-8655-packet-fix-race-condition.patch b/CVE-2016-8655-packet-fix-race-condition.patch
new file mode 100644 (file)
index 0000000..6c62ed4
--- /dev/null
+++ b/CVE-2016-8655-packet-fix-race-condition.patch
@@ -0,0 +1,92 @@
+From 84ac7260236a49c79eede91617700174c2c19b0c Mon Sep 17 00:00:00 2001
+From: Philip Pettersson <philip.pettersson@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@gmail.com>
+Signed-off-by: Eric Dumazet <edumazet@google.com>
+Signed-off-by: David S. Miller <davem@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
+

diff --git a/Makefile b/Makefile
index 0e44a85af0d18afd784682644eb3d71acc207c0a..4f2e5fcbaf277534f6f5dc5b4c473b4f2ba37cfc 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -268,6 +268,7 @@ ${KERNEL_SRC}/README ${KERNEL_CFG_ORG}: ${KERNELSRCTAR}
        # IPoIB performance regression fix
        cd ${KERNEL_SRC}; patch -p1 < ../IB-ipoib-move-back-the-IB-LL-address-into-the-hard-header.patch
        cd ${KERNEL_SRC}; patch -p1 < ../bnx2x-allow-adding-VLANs-while-interface-is-down.patch
+       cd ${KERNEL_SRC}; patch -p1 < ../CVE-2016-8655-packet-fix-race-condition.patch
        sed -i ${KERNEL_SRC}/Makefile -e 's/^EXTRAVERSION.*$$/EXTRAVERSION=${EXTRAVERSION}/'
        touch $@