From: "Mantas Mikulėnas" <grawity@gmail.com>
To: Tadeusz Struk <tadeusz.struk@intel.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
James.Bottomley@hansenpartnership.com,
linux-integrity@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] tpm: fix an invalid condition in tpm_common_poll
Date: Wed, 20 Mar 2019 20:51:30 +0200 [thread overview]
Message-ID: <CAPWNY8UmDAKeF+SNMKDxki=-=s+UPx9WXQvSoFqWmUCsNvv=1g@mail.gmail.com> (raw)
In-Reply-To: <155302749437.13955.651380639754310898.stgit@tstruk-mobl1.jf.intel.com>
On Tue, Mar 19, 2019 at 10:31 PM Tadeusz Struk <tadeusz.struk@intel.com> wrote:
>
> The poll condition should only check response_length,
> because reads should only be issued if there is data to read.
> The response_read flag only prevents double writes.
> The problem was that the write set the response_read to false,
> enqued a tpm job, and returned. Then application called poll
> which checked the response_read flag and returned EPOLLIN.
> Then the application called read, but got nothing.
> After all that the async_work kicked in.
> Added also mutex_lock around the poll check to prevent
> other possible race conditions.
>
> Fixes: 9488585b21bef0df12 ("tpm: add support for partial reads")
> Reported-by: Mantas Mikulėnas <grawity@gmail.com>
> Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
> ---
> drivers/char/tpm/tpm-dev-common.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
> index 5eecad233ea1..7312d3214381 100644
> --- a/drivers/char/tpm/tpm-dev-common.c
> +++ b/drivers/char/tpm/tpm-dev-common.c
> @@ -203,12 +203,14 @@ __poll_t tpm_common_poll(struct file *file, poll_table *wait)
> __poll_t mask = 0;
>
> poll_wait(file, &priv->async_wait, wait);
> + mutex_lock(&priv->buffer_mutex);
>
> - if (!priv->response_read || priv->response_length)
> + if (priv->response_length)
> mask = EPOLLIN | EPOLLRDNORM;
> else
> mask = EPOLLOUT | EPOLLWRNORM;
>
> + mutex_unlock(&priv->buffer_mutex);
> return mask;
> }
Thanks, this patch seems to work, and I apologize for not responding
to test the patches earlier.
Any chance it'll be submitted for stable 5.0.x as well?
--
Mantas Mikulėnas
next prev parent reply other threads:[~2019-03-20 18:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-19 20:31 [PATCH v2] tpm: fix an invalid condition in tpm_common_poll Tadeusz Struk
2019-03-20 14:30 ` James Bottomley
2019-03-20 14:49 ` Tadeusz Struk
2019-03-20 18:51 ` Mantas Mikulėnas [this message]
2019-03-20 19:18 ` Tadeusz Struk
2019-03-21 14:04 ` Jarkko Sakkinen
2019-03-21 13:59 ` Jarkko Sakkinen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAPWNY8UmDAKeF+SNMKDxki=-=s+UPx9WXQvSoFqWmUCsNvv=1g@mail.gmail.com' \
--to=grawity@gmail.com \
--cc=James.Bottomley@hansenpartnership.com \
--cc=jarkko.sakkinen@linux.intel.com \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=tadeusz.struk@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).