Messages in this thread | | | Subject | Re: [PATCH net] vhost: correctly remove wait queue during poll failure | From | Jason Wang <> | Date | Tue, 27 Mar 2018 17:43:14 +0800 |
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On 2018年03月27日 17:28, Darren Kenny wrote: > Hi Jason, > > On Tue, Mar 27, 2018 at 11:47:22AM +0800, Jason Wang wrote: >> We tried to remove vq poll from wait queue, but do not check whether >> or not it was in a list before. This will lead double free. Fixing >> this by checking poll->wqh to make sure it was in a list. > > This text seems at odds with the code below, instead of checking > poll-whq, you are removing that check... > > Maybe the text needs rewording?
Yes, I admit it's bad, thanks for pointing out.
How about:
"Fixing this by switching to use vhost_poll_stop() which zeros poll->wqh after removing poll from waitqueue to make sure it won't be freed twice."
Thanks
> > Thanks, > > Darren. > >> >> Reported-by: syzbot+c0272972b01b872e604a@syzkaller.appspotmail.com >> Fixes: 2b8b328b61c79 ("vhost_net: handle polling errors when setting >> backend") >> Signed-off-by: Jason Wang <jasowang@redhat.com> >> --- >> drivers/vhost/vhost.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c >> index 1b3e8d2d..5d5a9d9 100644 >> --- a/drivers/vhost/vhost.c >> +++ b/drivers/vhost/vhost.c >> @@ -212,8 +212,7 @@ int vhost_poll_start(struct vhost_poll *poll, >> struct file *file) >> if (mask) >> vhost_poll_wakeup(&poll->wait, 0, 0, poll_to_key(mask)); >> if (mask & EPOLLERR) { >> - if (poll->wqh) >> - remove_wait_queue(poll->wqh, &poll->wait); >> + vhost_poll_stop(poll); >> ret = -EINVAL; >> } >> >> -- >> 2.7.4 >>
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