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Date: Thu, 8 Jun 2017 01:00:17 +0200
From: Willy Tarreau <w@....eu>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
linux@...ck-us.net
Cc: Eric Dumazet <edumazet@...gle.com>,
"David S . Miller" <davem@...emloft.net>, Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 231/250] can: Fix kernel panic at security_sock_rcv_skb
From: Eric Dumazet <edumazet@...gle.com>
commit f1712c73714088a7252d276a57126d56c7d37e64 upstream.
Zhang Yanmin reported crashes [1] and provided a patch adding a
synchronize_rcu() call in can_rx_unregister()
The main problem seems that the sockets themselves are not RCU
protected.
If CAN uses RCU for delivery, then sockets should be freed only after
one RCU grace period.
Recent kernels could use sock_set_flag(sk, SOCK_RCU_FREE), but let's
ease stable backports with the following fix instead.
[1]
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff81495e25>] selinux_socket_sock_rcv_skb+0x65/0x2a0
Call Trace:
<IRQ>
[<ffffffff81485d8c>] security_sock_rcv_skb+0x4c/0x60
[<ffffffff81d55771>] sk_filter+0x41/0x210
[<ffffffff81d12913>] sock_queue_rcv_skb+0x53/0x3a0
[<ffffffff81f0a2b3>] raw_rcv+0x2a3/0x3c0
[<ffffffff81f06eab>] can_rcv_filter+0x12b/0x370
[<ffffffff81f07af9>] can_receive+0xd9/0x120
[<ffffffff81f07beb>] can_rcv+0xab/0x100
[<ffffffff81d362ac>] __netif_receive_skb_core+0xd8c/0x11f0
[<ffffffff81d36734>] __netif_receive_skb+0x24/0xb0
[<ffffffff81d37f67>] process_backlog+0x127/0x280
[<ffffffff81d36f7b>] net_rx_action+0x33b/0x4f0
[<ffffffff810c88d4>] __do_softirq+0x184/0x440
[<ffffffff81f9e86c>] do_softirq_own_stack+0x1c/0x30
<EOI>
[<ffffffff810c76fb>] do_softirq.part.18+0x3b/0x40
[<ffffffff810c8bed>] do_softirq+0x1d/0x20
[<ffffffff81d30085>] netif_rx_ni+0xe5/0x110
[<ffffffff8199cc87>] slcan_receive_buf+0x507/0x520
[<ffffffff8167ef7c>] flush_to_ldisc+0x21c/0x230
[<ffffffff810e3baf>] process_one_work+0x24f/0x670
[<ffffffff810e44ed>] worker_thread+0x9d/0x6f0
[<ffffffff810e4450>] ? rescuer_thread+0x480/0x480
[<ffffffff810ebafc>] kthread+0x12c/0x150
[<ffffffff81f9ccef>] ret_from_fork+0x3f/0x70
Reported-by: Zhang Yanmin <yanmin.zhang@...el.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Acked-by: Oliver Hartkopp <socketcan@...tkopp.net>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Willy Tarreau <w@....eu>
---
include/linux/can/core.h | 7 +++----
net/can/af_can.c | 12 ++++++++++--
net/can/af_can.h | 3 ++-
net/can/bcm.c | 4 ++--
net/can/gw.c | 2 +-
net/can/raw.c | 4 ++--
6 files changed, 20 insertions(+), 12 deletions(-)
diff --git a/include/linux/can/core.h b/include/linux/can/core.h
index 78c6c52..6bdc00b 100644
--- a/include/linux/can/core.h
+++ b/include/linux/can/core.h
@@ -45,10 +45,9 @@ struct can_proto {
extern int can_proto_register(const struct can_proto *cp);
extern void can_proto_unregister(const struct can_proto *cp);
-extern int can_rx_register(struct net_device *dev, canid_t can_id,
- canid_t mask,
- void (*func)(struct sk_buff *, void *),
- void *data, char *ident);
+int can_rx_register(struct net_device *dev, canid_t can_id, canid_t mask,
+ void (*func)(struct sk_buff *, void *),
+ void *data, char *ident, struct sock *sk);
extern void can_rx_unregister(struct net_device *dev, canid_t can_id,
canid_t mask,
diff --git a/net/can/af_can.c b/net/can/af_can.c
index d3668c5..34064aa 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -425,6 +425,7 @@ static struct hlist_head *find_rcv_list(canid_t *can_id, canid_t *mask,
* @func: callback function on filter match
* @data: returned parameter for callback function
* @ident: string for calling module indentification
+ * @sk: socket pointer (might be NULL)
*
* Description:
* Invokes the callback function with the received sk_buff and the given
@@ -448,7 +449,7 @@ static struct hlist_head *find_rcv_list(canid_t *can_id, canid_t *mask,
*/
int can_rx_register(struct net_device *dev, canid_t can_id, canid_t mask,
void (*func)(struct sk_buff *, void *), void *data,
- char *ident)
+ char *ident, struct sock *sk)
{
struct receiver *r;
struct hlist_head *rl;
@@ -476,6 +477,7 @@ int can_rx_register(struct net_device *dev, canid_t can_id, canid_t mask,
r->func = func;
r->data = data;
r->ident = ident;
+ r->sk = sk;
hlist_add_head_rcu(&r->list, rl);
d->entries++;
@@ -500,8 +502,11 @@ EXPORT_SYMBOL(can_rx_register);
static void can_rx_delete_receiver(struct rcu_head *rp)
{
struct receiver *r = container_of(rp, struct receiver, rcu);
+ struct sock *sk = r->sk;
kmem_cache_free(rcv_cache, r);
+ if (sk)
+ sock_put(sk);
}
/**
@@ -576,8 +581,11 @@ void can_rx_unregister(struct net_device *dev, canid_t can_id, canid_t mask,
spin_unlock(&can_rcvlists_lock);
/* schedule the receiver item for deletion */
- if (r)
+ if (r) {
+ if (r->sk)
+ sock_hold(r->sk);
call_rcu(&r->rcu, can_rx_delete_receiver);
+ }
}
EXPORT_SYMBOL(can_rx_unregister);
diff --git a/net/can/af_can.h b/net/can/af_can.h
index 1dccb4c..0e95be4 100644
--- a/net/can/af_can.h
+++ b/net/can/af_can.h
@@ -50,13 +50,14 @@
struct receiver {
struct hlist_node list;
- struct rcu_head rcu;
canid_t can_id;
canid_t mask;
unsigned long matches;
void (*func)(struct sk_buff *, void *);
void *data;
char *ident;
+ struct sock *sk;
+ struct rcu_head rcu;
};
enum { RX_ERR, RX_ALL, RX_FIL, RX_INV, RX_EFF, RX_MAX };
diff --git a/net/can/bcm.c b/net/can/bcm.c
index dd0781c..725ce81 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -1169,7 +1169,7 @@ static int bcm_rx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
err = can_rx_register(dev, op->can_id,
REGMASK(op->can_id),
bcm_rx_handler, op,
- "bcm");
+ "bcm", sk);
op->rx_reg_dev = dev;
dev_put(dev);
@@ -1178,7 +1178,7 @@ static int bcm_rx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
} else
err = can_rx_register(NULL, op->can_id,
REGMASK(op->can_id),
- bcm_rx_handler, op, "bcm");
+ bcm_rx_handler, op, "bcm", sk);
if (err) {
/* this bcm rx op is broken -> remove it */
list_del(&op->list);
diff --git a/net/can/gw.c b/net/can/gw.c
index de25455..2ad8aa4 100644
--- a/net/can/gw.c
+++ b/net/can/gw.c
@@ -435,7 +435,7 @@ static inline int cgw_register_filter(struct cgw_job *gwj)
{
return can_rx_register(gwj->src.dev, gwj->ccgw.filter.can_id,
gwj->ccgw.filter.can_mask, can_can_gw_rcv,
- gwj, "gw");
+ gwj, "gw", NULL);
}
static inline void cgw_unregister_filter(struct cgw_job *gwj)
diff --git a/net/can/raw.c b/net/can/raw.c
index 1085e65..f4d8648 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -168,7 +168,7 @@ static int raw_enable_filters(struct net_device *dev, struct sock *sk,
for (i = 0; i < count; i++) {
err = can_rx_register(dev, filter[i].can_id,
filter[i].can_mask,
- raw_rcv, sk, "raw");
+ raw_rcv, sk, "raw", sk);
if (err) {
/* clean up successfully registered filters */
while (--i >= 0)
@@ -189,7 +189,7 @@ static int raw_enable_errfilter(struct net_device *dev, struct sock *sk,
if (err_mask)
err = can_rx_register(dev, 0, err_mask | CAN_ERR_FLAG,
- raw_rcv, sk, "raw");
+ raw_rcv, sk, "raw", sk);
return err;
}
--
2.8.0.rc2.1.gbe9624a
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