104 lines
4.4 KiB
Diff
104 lines
4.4 KiB
Diff
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From patchwork Thu Mar 21 23:02:12 2019
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by orsmga004.jf.intel.com with ESMTP; 21 Mar 2019 16:02:13 -0700
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Subject: [PATCH v3] tpm: fix an invalid condition in tpm_common_poll
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From: Tadeusz Struk <tadeusz.struk@intel.com>
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To: jarkko.sakkinen@linux.intel.com
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Cc: grawity@gmail.com, James.Bottomley@HansenPartnership.com,
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linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
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stable@vger.kernel.org, tadeusz.struk@intel.com
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Date: Thu, 21 Mar 2019 16:02:12 -0700
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Message-ID:
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<155320933278.5015.1752135965699928631.stgit@tstruk-mobl1.jf.intel.com>
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The poll condition should only check response_length,
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because reads should only be issued if there is data to read.
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The response_read flag only prevents double writes.
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The problem was that the write set the response_read to false,
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enqued a tpm job, and returned. Then application called poll
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which checked the response_read flag and returned EPOLLIN.
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Then the application called read, but got nothing.
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After all that the async_work kicked in.
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Added also mutex_lock around the poll check to prevent
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other possible race conditions.
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Fixes: 9488585b21bef0df12 ("tpm: add support for partial reads")
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Reported-by: Mantas Mikulėnas <grawity@gmail.com>
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Tested-by: Mantas Mikulėnas <grawity@gmail.com>
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Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
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---
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drivers/char/tpm/tpm-dev-common.c | 4 +++-
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1 file changed, 3 insertions(+), 1 deletion(-)
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diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
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index 5eecad233ea1..7312d3214381 100644
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--- a/drivers/char/tpm/tpm-dev-common.c
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+++ b/drivers/char/tpm/tpm-dev-common.c
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@@ -203,12 +203,14 @@ __poll_t tpm_common_poll(struct file *file, poll_table *wait)
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__poll_t mask = 0;
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poll_wait(file, &priv->async_wait, wait);
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+ mutex_lock(&priv->buffer_mutex);
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- if (!priv->response_read || priv->response_length)
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+ if (priv->response_length)
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mask = EPOLLIN | EPOLLRDNORM;
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else
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mask = EPOLLOUT | EPOLLWRNORM;
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+ mutex_unlock(&priv->buffer_mutex);
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return mask;
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}
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