From: Tadeusz Struk <tadeusz.struk@intel.com>
To: jarkko.sakkinen@linux.intel.com
Cc: grawity@gmail.com, James.Bottomley@HansenPartnership.com,
linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org, tadeusz.struk@intel.com
Subject: [PATCH v3] tpm: fix an invalid condition in tpm_common_poll
Date: Thu, 21 Mar 2019 16:02:12 -0700 [thread overview]
Message-ID: <155320933278.5015.1752135965699928631.stgit@tstruk-mobl1.jf.intel.com> (raw)
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>
Tested-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;
}
next reply other threads:[~2019-03-21 23:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-21 23:02 Tadeusz Struk [this message]
2019-03-22 5:18 ` [PATCH v3] tpm: fix an invalid condition in tpm_common_poll Greg KH
2019-03-22 11:34 ` 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=155320933278.5015.1752135965699928631.stgit@tstruk-mobl1.jf.intel.com \
--to=tadeusz.struk@intel.com \
--cc=James.Bottomley@HansenPartnership.com \
--cc=grawity@gmail.com \
--cc=jarkko.sakkinen@linux.intel.com \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=stable@vger.kernel.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.