* [PATCH v3] tpm: fix an invalid condition in tpm_common_poll
@ 2019-03-21 23:02 Tadeusz Struk
2019-03-22 5:18 ` Greg KH
2019-03-22 11:34 ` Jarkko Sakkinen
0 siblings, 2 replies; 3+ messages in thread
From: Tadeusz Struk @ 2019-03-21 23:02 UTC (permalink / raw)
To: jarkko.sakkinen
Cc: grawity, James.Bottomley, linux-integrity, linux-kernel, stable,
tadeusz.struk
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;
}
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v3] tpm: fix an invalid condition in tpm_common_poll
2019-03-21 23:02 [PATCH v3] tpm: fix an invalid condition in tpm_common_poll Tadeusz Struk
@ 2019-03-22 5:18 ` Greg KH
2019-03-22 11:34 ` Jarkko Sakkinen
1 sibling, 0 replies; 3+ messages in thread
From: Greg KH @ 2019-03-22 5:18 UTC (permalink / raw)
To: Tadeusz Struk
Cc: jarkko.sakkinen, grawity, James.Bottomley, linux-integrity,
linux-kernel, stable
On Thu, Mar 21, 2019 at 04:02:12PM -0700, Tadeusz Struk 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>
> 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(-)
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3] tpm: fix an invalid condition in tpm_common_poll
2019-03-21 23:02 [PATCH v3] tpm: fix an invalid condition in tpm_common_poll Tadeusz Struk
2019-03-22 5:18 ` Greg KH
@ 2019-03-22 11:34 ` Jarkko Sakkinen
1 sibling, 0 replies; 3+ messages in thread
From: Jarkko Sakkinen @ 2019-03-22 11:34 UTC (permalink / raw)
To: Tadeusz Struk
Cc: grawity, James.Bottomley, linux-integrity, linux-kernel, stable
On Thu, Mar 21, 2019 at 04:02:12PM -0700, Tadeusz Struk 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.
>
Cc: stable@vger.kernel.org
is missing here.
> 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>
/Jarkko
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-03-21 23:02 [PATCH v3] tpm: fix an invalid condition in tpm_common_poll Tadeusz Struk
2019-03-22 5:18 ` Greg KH
2019-03-22 11:34 ` Jarkko Sakkinen
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