| Message ID | 155371155820.17863.10580533125620125669.stgit@tstruk-mobl1.jf.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v4] tpm: fix an invalid condition in tpm_common_poll | expand |
On Wed, Mar 27, 2019 at 11:32:38AM -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 > 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> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Thank you, it is applied. /Jarkko
On 3/28/19 5:34 AM, Jarkko Sakkinen wrote:
> Thank you, it is applied.
Thank you Jarkko.
Hello Jarkko, On Thu, Mar 28, 2019 at 09:34:18AM -0700, Tadeusz Struk wrote: > On 3/28/19 5:34 AM, Jarkko Sakkinen wrote: > > Thank you, it is applied. > > Thank you Jarkko. What's the status of this patch now? It's needed in linux-5.0.y as TPM 2.0 support is currently broken with those stable kernels without this commit. Thanks,
On Mon, Apr 08, 2019 at 02:01:38PM +0200, Thibaut Sautereau wrote: > Hello Jarkko, > > On Thu, Mar 28, 2019 at 09:34:18AM -0700, Tadeusz Struk wrote: > > On 3/28/19 5:34 AM, Jarkko Sakkinen wrote: > > > Thank you, it is applied. > > > > Thank you Jarkko. > > What's the status of this patch now? It's needed in linux-5.0.y as TPM > 2.0 support is currently broken with those stable kernels without this > commit. part of a PR. https://lore.kernel.org/linux-integrity/20190329115544.GA27351@linux.intel.com/ /Jarkko
On 2019-04-09 15:44, Jarkko Sakkinen wrote: > On Mon, Apr 08, 2019 at 02:01:38PM +0200, Thibaut Sautereau wrote: >> [...] >> What's the status of this patch now? It's needed in linux-5.0.y as TPM >> 2.0 support is currently broken with those stable kernels without this >> commit. > > part of a PR. > > https://lore.kernel.org/linux-integrity/20190329115544.GA27351@linux.intel.com/ It appears that the final version of the patch that was merged to Linus's tree [1] does not include the "Cc: stable@vger.kernel.org" tag. If I understand correctly, this means that the patch will not be automatically included in the -stable tree without further action. Is there a specific reason not to apply this patch to 5.0.x, or did the tag just get lost in the merge process? Cheers, Jonas [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7110629263469b4664d00b38ef80a656eddf3637
On Tue, Apr 23, 2019 at 10:54:47PM +0200, Jonas Witschel wrote: >On 2019-04-09 15:44, Jarkko Sakkinen wrote: >> On Mon, Apr 08, 2019 at 02:01:38PM +0200, Thibaut Sautereau wrote: >>> [...] >>> What's the status of this patch now? It's needed in linux-5.0.y as TPM >>> 2.0 support is currently broken with those stable kernels without this >>> commit. >> >> part of a PR. >> >> https://lore.kernel.org/linux-integrity/20190329115544.GA27351@linux.intel.com/ > >It appears that the final version of the patch that was merged to >Linus's tree [1] does not include the "Cc: stable@vger.kernel.org" tag. >If I understand correctly, this means that the patch will not be >automatically included in the -stable tree without further action. Is >there a specific reason not to apply this patch to 5.0.x, or did the tag >just get lost in the merge process? Good catch; I see that Jarkko had the same comment on v3 but v4 ended up being without the -stable tag without any explanation. I've queued this for 5.0, it doesn't seem relevant for older branches. -- Thanks, Sasha
On 2019-04-24 02:43, Sasha Levin wrote: > On Tue, Apr 23, 2019 at 10:54:47PM +0200, Jonas Witschel wrote: >> On 2019-04-09 15:44, Jarkko Sakkinen wrote: >>> On Mon, Apr 08, 2019 at 02:01:38PM +0200, Thibaut Sautereau wrote: >>>> [...] >>>> What's the status of this patch now? It's needed in linux-5.0.y as TPM >>>> 2.0 support is currently broken with those stable kernels without this >>>> commit. >>> >>> part of a PR. >>> >>> https://lore.kernel.org/linux-integrity/20190329115544.GA27351@linux.intel.com/ >>> >> >> It appears that the final version of the patch that was merged to >> Linus's tree [1] does not include the "Cc: stable@vger.kernel.org" tag. >> If I understand correctly, this means that the patch will not be >> automatically included in the -stable tree without further action. Is >> there a specific reason not to apply this patch to 5.0.x, or did the tag >> just get lost in the merge process? > > Good catch; I see that Jarkko had the same comment on v3 but v4 ended up > being without the -stable tag without any explanation. I've queued this > for 5.0, it doesn't seem relevant for older branches. Thank you! Correct, the regression only affects 5.0. Regards, Jonas
On Tue, Apr 23, 2019 at 10:54:47PM +0200, Jonas Witschel wrote: > On 2019-04-09 15:44, Jarkko Sakkinen wrote: > > On Mon, Apr 08, 2019 at 02:01:38PM +0200, Thibaut Sautereau wrote: > >> [...] > >> What's the status of this patch now? It's needed in linux-5.0.y as TPM > >> 2.0 support is currently broken with those stable kernels without this > >> commit. > > > > part of a PR. > > > > https://lore.kernel.org/linux-integrity/20190329115544.GA27351@linux.intel.com/ > > It appears that the final version of the patch that was merged to > Linus's tree [1] does not include the "Cc: stable@vger.kernel.org" tag. > If I understand correctly, this means that the patch will not be > automatically included in the -stable tree without further action. Is > there a specific reason not to apply this patch to 5.0.x, or did the tag It is my mistake. What I can do is to post it manually to stable. I promise to do it as soon as it reaches the mainline. /Jarkko
diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c index 5eecad233ea1..744b0237300a 100644 --- a/drivers/char/tpm/tpm-dev-common.c +++ b/drivers/char/tpm/tpm-dev-common.c @@ -203,12 +203,19 @@ __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) + /* + * The response_length indicates if there is still response + * (or part of it) to be consumed. Partial reads decrease it + * by the number of bytes read, and write resets it the zero. + */ + if (priv->response_length) mask = EPOLLIN | EPOLLRDNORM; else mask = EPOLLOUT | EPOLLWRNORM; + mutex_unlock(&priv->buffer_mutex); return mask; }
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 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 | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)