| Message ID | 20220208200026.13783-1-socketcan@hartkopp.net (mailing list archive) |
|---|---|
| State | Awaiting Upstream |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | can: isotp: fix potential CAN frame reception race in isotp_rcv() | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Series ignored based on subject, async |
On 08.02.2022 21:00:26, 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> Applied to linux-can/testing. Added stable on Cc. Marc
diff --git a/net/can/isotp.c b/net/can/isotp.c index 02cbcb2ecf0d..9149e8d8aefc 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; /* protect single thread state machine */ }; static LIST_HEAD(isotp_notifier_list); static DEFINE_SPINLOCK(isotp_notifier_lock); static struct isotp_sock *isotp_busy_notifier; @@ -613,15 +615,21 @@ 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. + */ + spin_lock(&so->rx_lock); + 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; } switch (n_pci_type) { case N_PCI_FC: /* tx path: flow control frame containing the FC parameters */ @@ -666,10 +674,13 @@ 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 +1453,11 @@ 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);
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, 13 insertions(+), 1 deletion(-)