The commit is pushed to "branch-rh7-3.10.0-327.36.1.vz7.20.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.36.1.vz7.20.11
------>
commit e8993d723121f3d9303db373849bcd01df2def48
Author: Philip Pettersson <[email protected]>
Date: Wed Nov 30 14:55:36 2016 -0800
ms/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 <[email protected]>
Signed-off-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
============================================================
CVE-2016-8655: Linux af_packet.c race condition (local root)
Philip Pettersson discovered a race condition in the af_packet
implementation
in the Linux kernel. A local unprivileged attacker could use this to cause a
denial of service (system crash) or run arbitrary code with administrative
privileges.
https://jira.sw.ru/browse/PSBM-56699
---
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 2a1b15a..0e662e3 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3313,19 +3313,25 @@ 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:
{
@@ -3781,6 +3787,7 @@ 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)) {
WARN(1, "Tx-ring is not supported.\n");
@@ -3869,7 +3876,6 @@ 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);
@@ -3918,7 +3924,6 @@ static int packet_set_ring(struct sock *sk, union
tpacket_req_u *req_u,
if (!tx_ring)
prb_shutdown_retire_blk_timer(po, tx_ring, rb_queue);
}
- release_sock(sk);
if (pg_vec) {
if (psc)
@@ -3927,6 +3932,7 @@ static int packet_set_ring(struct sock *sk, union
tpacket_req_u *req_u,
free_pg_vec(pg_vec, order, req->tp_block_nr);
}
out:
+ release_sock(sk);
return err;
}
_______________________________________________
Devel mailing list
[email protected]
https://lists.openvz.org/mailman/listinfo/devel
