* [RFC][PATCH v2] can: isotp: fix CAN frame reception race in isotp_rcv()
@ 2022-01-28 7:43 Oliver Hartkopp
2022-01-28 7:56 ` Marc Kleine-Budde
0 siblings, 1 reply; 3+ messages in thread
From: Oliver Hartkopp @ 2022-01-28 7:43 UTC (permalink / raw)
To: netdev, linux-can, william.xuanziyang
Cc: Oliver Hartkopp, syzbot+4c63f36709a642f801c5
When receiving a CAN frame the current code logic does not consider
concurrently receiving processes which do not show up in real world
usage.
Ziyang Xuan writes:
The following syz problem is one of the scenarios. so->rx.len is
changed by isotp_rcv_ff() during isotp_rcv_cf(), so->rx.len equals
0 before alloc_skb() and equals 4096 after alloc_skb(). That will
trigger skb_over_panic() in skb_put().
=======================================================
CPU: 1 PID: 19 Comm: ksoftirqd/1 Not tainted 5.16.0-rc8-syzkaller #0
RIP: 0010:skb_panic+0x16c/0x16e net/core/skbuff.c:113
Call Trace:
<TASK>
skb_over_panic net/core/skbuff.c:118 [inline]
skb_put.cold+0x24/0x24 net/core/skbuff.c:1990
isotp_rcv_cf net/can/isotp.c:570 [inline]
isotp_rcv+0xa38/0x1e30 net/can/isotp.c:668
deliver net/can/af_can.c:574 [inline]
can_rcv_filter+0x445/0x8d0 net/can/af_can.c:635
can_receive+0x31d/0x580 net/can/af_can.c:665
can_rcv+0x120/0x1c0 net/can/af_can.c:696
__netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5465
__netif_receive_skb+0x24/0x1b0 net/core/dev.c:5579
Therefore we make sure the state changes and data structures stay
consistent at CAN frame reception time by adding a spin_lock in
isotp_rcv(). This fixes the issue reported by syzkaller but does not
affect real world operation.
Link: https://lore.kernel.org/linux-can/d7e69278-d741-c706-65e1-e87623d9a8e8@huawei.com/T/
Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol")
Reported-by: syzbot+4c63f36709a642f801c5@syzkaller.appspotmail.com
Reported-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
net/can/isotp.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/net/can/isotp.c b/net/can/isotp.c
index 02cbcb2ecf0d..b5ba1a9a9e3b 100644
--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -54,10 +54,11 @@
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/interrupt.h>
+#include <linux/spinlock.h>
#include <linux/hrtimer.h>
#include <linux/wait.h>
#include <linux/uio.h>
#include <linux/net.h>
#include <linux/netdevice.h>
@@ -143,10 +144,11 @@ struct isotp_sock {
u32 force_tx_stmin;
u32 force_rx_stmin;
struct tpcon rx, tx;
struct list_head notifier;
wait_queue_head_t wait;
+ spinlock_t rx_lock;
};
static LIST_HEAD(isotp_notifier_list);
static DEFINE_SPINLOCK(isotp_notifier_lock);
static struct isotp_sock *isotp_busy_notifier;
@@ -613,10 +615,19 @@ static void isotp_rcv(struct sk_buff *skb, void *data)
if (ae && cf->data[0] != so->opt.rx_ext_address)
return;
n_pci_type = cf->data[ae] & 0xF0;
+ /* Make sure the state changes and data structures stay consistent at
+ * CAN frame reception time. This locking is not needed in real world
+ * use cases but the inconsistency can be triggered with syzkaller.
+ *
+ * To not lock up the softirq just drop the frame in syzcaller case.
+ */
+ if (!spin_trylock(&so->rx_lock))
+ return;
+
if (so->opt.flags & CAN_ISOTP_HALF_DUPLEX) {
/* check rx/tx path half duplex expectations */
if ((so->tx.state != ISOTP_IDLE && n_pci_type != N_PCI_FC) ||
(so->rx.state != ISOTP_IDLE && n_pci_type == N_PCI_FC))
return;
@@ -666,10 +677,12 @@ static void isotp_rcv(struct sk_buff *skb, void *data)
case N_PCI_CF:
/* rx path: consecutive frame */
isotp_rcv_cf(sk, cf, ae, skb);
break;
}
+
+ spin_unlock(&so->rx_lock);
}
static void isotp_fill_dataframe(struct canfd_frame *cf, struct isotp_sock *so,
int ae, int off)
{
@@ -1442,10 +1455,11 @@ static int isotp_init(struct sock *sk)
so->rxtimer.function = isotp_rx_timer_handler;
hrtimer_init(&so->txtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
so->txtimer.function = isotp_tx_timer_handler;
init_waitqueue_head(&so->wait);
+ spin_lock_init(&so->rx_lock);
spin_lock(&isotp_notifier_lock);
list_add_tail(&so->notifier, &isotp_notifier_list);
spin_unlock(&isotp_notifier_lock);
--
2.30.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [RFC][PATCH v2] can: isotp: fix CAN frame reception race in isotp_rcv()
2022-01-28 7:43 [RFC][PATCH v2] can: isotp: fix CAN frame reception race in isotp_rcv() Oliver Hartkopp
@ 2022-01-28 7:56 ` Marc Kleine-Budde
2022-01-28 8:01 ` Oliver Hartkopp
0 siblings, 1 reply; 3+ messages in thread
From: Marc Kleine-Budde @ 2022-01-28 7:56 UTC (permalink / raw)
To: Oliver Hartkopp
Cc: netdev, linux-can, william.xuanziyang, syzbot+4c63f36709a642f801c5
[-- Attachment #1: Type: text/plain, Size: 4872 bytes --]
On 28.01.2022 08:43:27, Oliver Hartkopp wrote:
> When receiving a CAN frame the current code logic does not consider
> concurrently receiving processes which do not show up in real world
> usage.
>
> Ziyang Xuan writes:
>
> The following syz problem is one of the scenarios. so->rx.len is
> changed by isotp_rcv_ff() during isotp_rcv_cf(), so->rx.len equals
> 0 before alloc_skb() and equals 4096 after alloc_skb(). That will
> trigger skb_over_panic() in skb_put().
>
> =======================================================
> CPU: 1 PID: 19 Comm: ksoftirqd/1 Not tainted 5.16.0-rc8-syzkaller #0
> RIP: 0010:skb_panic+0x16c/0x16e net/core/skbuff.c:113
> Call Trace:
> <TASK>
> skb_over_panic net/core/skbuff.c:118 [inline]
> skb_put.cold+0x24/0x24 net/core/skbuff.c:1990
> isotp_rcv_cf net/can/isotp.c:570 [inline]
> isotp_rcv+0xa38/0x1e30 net/can/isotp.c:668
> deliver net/can/af_can.c:574 [inline]
> can_rcv_filter+0x445/0x8d0 net/can/af_can.c:635
> can_receive+0x31d/0x580 net/can/af_can.c:665
> can_rcv+0x120/0x1c0 net/can/af_can.c:696
> __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5465
> __netif_receive_skb+0x24/0x1b0 net/core/dev.c:5579
>
> Therefore we make sure the state changes and data structures stay
> consistent at CAN frame reception time by adding a spin_lock in
> isotp_rcv(). This fixes the issue reported by syzkaller but does not
> affect real world operation.
>
> Link: https://lore.kernel.org/linux-can/d7e69278-d741-c706-65e1-e87623d9a8e8@huawei.com/T/
> Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol")
> Reported-by: syzbot+4c63f36709a642f801c5@syzkaller.appspotmail.com
> Reported-by: Ziyang Xuan <william.xuanziyang@huawei.com>
> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
> ---
> net/can/isotp.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/net/can/isotp.c b/net/can/isotp.c
> index 02cbcb2ecf0d..b5ba1a9a9e3b 100644
> --- a/net/can/isotp.c
> +++ b/net/can/isotp.c
> @@ -54,10 +54,11 @@
> */
>
> #include <linux/module.h>
> #include <linux/init.h>
> #include <linux/interrupt.h>
> +#include <linux/spinlock.h>
> #include <linux/hrtimer.h>
> #include <linux/wait.h>
> #include <linux/uio.h>
> #include <linux/net.h>
> #include <linux/netdevice.h>
> @@ -143,10 +144,11 @@ struct isotp_sock {
> u32 force_tx_stmin;
> u32 force_rx_stmin;
> struct tpcon rx, tx;
> struct list_head notifier;
> wait_queue_head_t wait;
> + spinlock_t rx_lock;
I think checkpatch wants to have a comment describing the lock.
> };
>
> static LIST_HEAD(isotp_notifier_list);
> static DEFINE_SPINLOCK(isotp_notifier_lock);
> static struct isotp_sock *isotp_busy_notifier;
> @@ -613,10 +615,19 @@ static void isotp_rcv(struct sk_buff *skb, void *data)
> if (ae && cf->data[0] != so->opt.rx_ext_address)
> return;
>
> n_pci_type = cf->data[ae] & 0xF0;
>
> + /* Make sure the state changes and data structures stay consistent at
> + * CAN frame reception time. This locking is not needed in real world
> + * use cases but the inconsistency can be triggered with syzkaller.
> + *
> + * To not lock up the softirq just drop the frame in syzcaller case.
> + */
> + if (!spin_trylock(&so->rx_lock))
> + return;
> +
> if (so->opt.flags & CAN_ISOTP_HALF_DUPLEX) {
> /* check rx/tx path half duplex expectations */
> if ((so->tx.state != ISOTP_IDLE && n_pci_type != N_PCI_FC) ||
> (so->rx.state != ISOTP_IDLE && n_pci_type == N_PCI_FC))
> return;
^^^^^^
goto out_unlock;
Maybe there are more returns, which are not shown in the context of this
patch.
> @@ -666,10 +677,12 @@ static void isotp_rcv(struct sk_buff *skb, void *data)
> case N_PCI_CF:
> /* rx path: consecutive frame */
> isotp_rcv_cf(sk, cf, ae, skb);
> break;
> }
> +
out_unlock:
> + spin_unlock(&so->rx_lock);
> }
>
> static void isotp_fill_dataframe(struct canfd_frame *cf, struct isotp_sock *so,
> int ae, int off)
> {
> @@ -1442,10 +1455,11 @@ static int isotp_init(struct sock *sk)
> so->rxtimer.function = isotp_rx_timer_handler;
> hrtimer_init(&so->txtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
> so->txtimer.function = isotp_tx_timer_handler;
>
> init_waitqueue_head(&so->wait);
> + spin_lock_init(&so->rx_lock);
>
> spin_lock(&isotp_notifier_lock);
> list_add_tail(&so->notifier, &isotp_notifier_list);
> spin_unlock(&isotp_notifier_lock);
regards,
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC][PATCH v2] can: isotp: fix CAN frame reception race in isotp_rcv()
2022-01-28 7:56 ` Marc Kleine-Budde
@ 2022-01-28 8:01 ` Oliver Hartkopp
0 siblings, 0 replies; 3+ messages in thread
From: Oliver Hartkopp @ 2022-01-28 8:01 UTC (permalink / raw)
To: Marc Kleine-Budde
Cc: netdev, linux-can, william.xuanziyang, syzbot+4c63f36709a642f801c5
On 28.01.22 08:56, Marc Kleine-Budde wrote:
> On 28.01.2022 08:43:27, Oliver Hartkopp wrote:
>> When receiving a CAN frame the current code logic does not consider
>> concurrently receiving processes which do not show up in real world
>> usage.
>>
>> Ziyang Xuan writes:
>>
>> The following syz problem is one of the scenarios. so->rx.len is
>> changed by isotp_rcv_ff() during isotp_rcv_cf(), so->rx.len equals
>> 0 before alloc_skb() and equals 4096 after alloc_skb(). That will
>> trigger skb_over_panic() in skb_put().
>>
>> =======================================================
>> CPU: 1 PID: 19 Comm: ksoftirqd/1 Not tainted 5.16.0-rc8-syzkaller #0
>> RIP: 0010:skb_panic+0x16c/0x16e net/core/skbuff.c:113
>> Call Trace:
>> <TASK>
>> skb_over_panic net/core/skbuff.c:118 [inline]
>> skb_put.cold+0x24/0x24 net/core/skbuff.c:1990
>> isotp_rcv_cf net/can/isotp.c:570 [inline]
>> isotp_rcv+0xa38/0x1e30 net/can/isotp.c:668
>> deliver net/can/af_can.c:574 [inline]
>> can_rcv_filter+0x445/0x8d0 net/can/af_can.c:635
>> can_receive+0x31d/0x580 net/can/af_can.c:665
>> can_rcv+0x120/0x1c0 net/can/af_can.c:696
>> __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5465
>> __netif_receive_skb+0x24/0x1b0 net/core/dev.c:5579
>>
>> Therefore we make sure the state changes and data structures stay
>> consistent at CAN frame reception time by adding a spin_lock in
>> isotp_rcv(). This fixes the issue reported by syzkaller but does not
>> affect real world operation.
>>
>> Link: https://lore.kernel.org/linux-can/d7e69278-d741-c706-65e1-e87623d9a8e8@huawei.com/T/
>> Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol")
>> Reported-by: syzbot+4c63f36709a642f801c5@syzkaller.appspotmail.com
>> Reported-by: Ziyang Xuan <william.xuanziyang@huawei.com>
>> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
>> ---
>> net/can/isotp.c | 14 ++++++++++++++
>> 1 file changed, 14 insertions(+)
>>
>> diff --git a/net/can/isotp.c b/net/can/isotp.c
>> index 02cbcb2ecf0d..b5ba1a9a9e3b 100644
>> --- a/net/can/isotp.c
>> +++ b/net/can/isotp.c
>> @@ -54,10 +54,11 @@
>> */
>>
>> #include <linux/module.h>
>> #include <linux/init.h>
>> #include <linux/interrupt.h>
>> +#include <linux/spinlock.h>
>> #include <linux/hrtimer.h>
>> #include <linux/wait.h>
>> #include <linux/uio.h>
>> #include <linux/net.h>
>> #include <linux/netdevice.h>
>> @@ -143,10 +144,11 @@ struct isotp_sock {
>> u32 force_tx_stmin;
>> u32 force_rx_stmin;
>> struct tpcon rx, tx;
>> struct list_head notifier;
>> wait_queue_head_t wait;
>> + spinlock_t rx_lock;
>
> I think checkpatch wants to have a comment describing the lock.
Ok.
>
>> };
>>
>> static LIST_HEAD(isotp_notifier_list);
>> static DEFINE_SPINLOCK(isotp_notifier_lock);
>> static struct isotp_sock *isotp_busy_notifier;
>> @@ -613,10 +615,19 @@ static void isotp_rcv(struct sk_buff *skb, void *data)
>> if (ae && cf->data[0] != so->opt.rx_ext_address)
>> return;
>>
>> n_pci_type = cf->data[ae] & 0xF0;
>>
>> + /* Make sure the state changes and data structures stay consistent at
>> + * CAN frame reception time. This locking is not needed in real world
>> + * use cases but the inconsistency can be triggered with syzkaller.
>> + *
>> + * To not lock up the softirq just drop the frame in syzcaller case.
>> + */
>> + if (!spin_trylock(&so->rx_lock))
>> + return;
>> +
>> if (so->opt.flags & CAN_ISOTP_HALF_DUPLEX) {
>> /* check rx/tx path half duplex expectations */
>> if ((so->tx.state != ISOTP_IDLE && n_pci_type != N_PCI_FC) ||
>> (so->rx.state != ISOTP_IDLE && n_pci_type == N_PCI_FC))
>> return;
> ^^^^^^
> goto out_unlock;
>
> Maybe there are more returns, which are not shown in the context of this
> patch.
>
Oh, yes! Thanks!
Will send a V3 soon.
>> @@ -666,10 +677,12 @@ static void isotp_rcv(struct sk_buff *skb, void *data)
>> case N_PCI_CF:
>> /* rx path: consecutive frame */
>> isotp_rcv_cf(sk, cf, ae, skb);
>> break;
>> }
>> +
> out_unlock:
>> + spin_unlock(&so->rx_lock);
>> }
>>
>> static void isotp_fill_dataframe(struct canfd_frame *cf, struct isotp_sock *so,
>> int ae, int off)
>> {
>> @@ -1442,10 +1455,11 @@ static int isotp_init(struct sock *sk)
>> so->rxtimer.function = isotp_rx_timer_handler;
>> hrtimer_init(&so->txtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
>> so->txtimer.function = isotp_tx_timer_handler;
>>
>> init_waitqueue_head(&so->wait);
>> + spin_lock_init(&so->rx_lock);
>>
>> spin_lock(&isotp_notifier_lock);
>> list_add_tail(&so->notifier, &isotp_notifier_list);
>> spin_unlock(&isotp_notifier_lock);
>
> regards,
> Marc
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-01-28 7:43 [RFC][PATCH v2] can: isotp: fix CAN frame reception race in isotp_rcv() Oliver Hartkopp
2022-01-28 7:56 ` Marc Kleine-Budde
2022-01-28 8:01 ` Oliver Hartkopp
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