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SubjectRe: [PATCH net v2 1/2] can: isotp: add result check for wait_event_interruptible()
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On 09.10.21 09:40, Ziyang Xuan wrote:
> Using wait_event_interruptible() to wait for complete transmission,
> but do not check the result of wait_event_interruptible() which can
> be interrupted. It will result in tx buffer has multiple accessers
> and the later process interferes with the previous process.
>
> Following is one of the problems reported by syzbot.
>
> =============================================================
> WARNING: CPU: 0 PID: 0 at net/can/isotp.c:840 isotp_tx_timer_handler+0x2e0/0x4c0
> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.13.0-rc7+ #68
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014
> RIP: 0010:isotp_tx_timer_handler+0x2e0/0x4c0
> Call Trace:
> <IRQ>
> ? isotp_setsockopt+0x390/0x390
> __hrtimer_run_queues+0xb8/0x610
> hrtimer_run_softirq+0x91/0xd0
> ? rcu_read_lock_sched_held+0x4d/0x80
> __do_softirq+0xe8/0x553
> irq_exit_rcu+0xf8/0x100
> sysvec_apic_timer_interrupt+0x9e/0xc0
> </IRQ>
> asm_sysvec_apic_timer_interrupt+0x12/0x20
>
> Add result check for wait_event_interruptible() in isotp_sendmsg()
> to avoid multiple accessers for tx buffer.
>
> Reported-by: syzbot+78bab6958a614b0c80b9@syzkaller.appspotmail.com
> Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol")
> Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>

Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>

Many thanks!
Oliver

> ---
> net/can/isotp.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/net/can/isotp.c b/net/can/isotp.c
> index caaa532ece94..2ac29c2b2ca6 100644
> --- a/net/can/isotp.c
> +++ b/net/can/isotp.c
> @@ -865,7 +865,9 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
> return -EAGAIN;
>
> /* wait for complete transmission of current pdu */
> - wait_event_interruptible(so->wait, so->tx.state == ISOTP_IDLE);
> + err = wait_event_interruptible(so->wait, so->tx.state == ISOTP_IDLE);
> + if (err)
> + return err;
> }
>
> if (!size || size > MAX_MSG_LENGTH)
>

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