[PATCH -next] tpm: change the return type of calc_tpm2_event_size to size_t

[PATCH -next] tpm: change the return type of calc_tpm2_event_size to size_t

[YueHaibing]

calc_tpm2_event_size return size of the event which type is
size_t, If it is an invalid event, returns 0. And all the
caller use a size_t variable to check the return value, so
no need to convert to the return value type to int.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
---
 drivers/char/tpm/eventlog/tpm2.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/char/tpm/eventlog/tpm2.c b/drivers/char/tpm/eventlog/tpm2.c
index d8b7713..f824563 100644
--- a/drivers/char/tpm/eventlog/tpm2.c
+++ b/drivers/char/tpm/eventlog/tpm2.c
@@ -37,8 +37,8 @@
  *
  * Returns size of the event. If it is an invalid event, returns 0.
  */
-static int calc_tpm2_event_size(struct tcg_pcr_event2_head *event,
-				struct tcg_pcr_event *event_header)
+static size_t calc_tpm2_event_size(struct tcg_pcr_event2_head *event,
+				   struct tcg_pcr_event *event_header)
 {
 	struct tcg_efi_specid_event_head *efispecid;
 	struct tcg_event_field *event_field;
-- 
2.7.0

Re: [PATCH -next] tpm: change the return type of calc_tpm2_event_size to size_t

[Jarkko Sakkinen]

On Tue, Feb 19, 2019 at 03:26:18PM +0800, YueHaibing wrote:
> calc_tpm2_event_size return size of the event which type is
> size_t, If it is an invalid event, returns 0. And all the
> caller use a size_t variable to check the return value, so
> no need to convert to the return value type to int.
> 
> Signed-off-by: YueHaibing <yuehaibing@huawei.com>

I don't see this patch make any value.

/Jarkko

Re: [PATCH -next] tpm: change the return type of calc_tpm2_event_size to size_t

[YueHaibing]

On 2019/2/19 16:59, Jarkko Sakkinen wrote:
> On Tue, Feb 19, 2019 at 03:26:18PM +0800, YueHaibing wrote:
>> calc_tpm2_event_size return size of the event which type is
>> size_t, If it is an invalid event, returns 0. And all the
>> caller use a size_t variable to check the return value, so
>> no need to convert to the return value type to int.
>>
>> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
> 
> I don't see this patch make any value.

calc_tpm2_event_size return size_t 'size' which derive from u32 'event_field->event_size',

convert it to int may result in truncation.

> 
> /Jarkko
> 
> .
> 

Re: [PATCH -next] tpm: change the return type of calc_tpm2_event_size to size_t

[Jarkko Sakkinen]

On Tue, Feb 19, 2019 at 05:15:47PM +0800, YueHaibing wrote:
> On 2019/2/19 16:59, Jarkko Sakkinen wrote:
> > On Tue, Feb 19, 2019 at 03:26:18PM +0800, YueHaibing wrote:
> >> calc_tpm2_event_size return size of the event which type is
> >> size_t, If it is an invalid event, returns 0. And all the
> >> caller use a size_t variable to check the return value, so
> >> no need to convert to the return value type to int.
> >>
> >> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
> > 
> > I don't see this patch make any value.
> 
> calc_tpm2_event_size return size_t 'size' which derive from u32 'event_field->event_size',
> 
> convert it to int may result in truncation.

Two remarks:

- Your real name is formatted incorrectly. It should be like "Yue Haibig"
  as shown in [1].
- If there is no actual regression, this change is useless.

[1] https://www.kernel.org/doc/html/v4.17/process/submitting-patches.html

/Jarkko

Re: [PATCH -next] tpm: change the return type of calc_tpm2_event_size to size_t

[YueHaibing]

On 2019/2/19 18:35, Jarkko Sakkinen wrote:
> On Tue, Feb 19, 2019 at 05:15:47PM +0800, YueHaibing wrote:
>> On 2019/2/19 16:59, Jarkko Sakkinen wrote:
>>> On Tue, Feb 19, 2019 at 03:26:18PM +0800, YueHaibing wrote:
>>>> calc_tpm2_event_size return size of the event which type is
>>>> size_t, If it is an invalid event, returns 0. And all the
>>>> caller use a size_t variable to check the return value, so
>>>> no need to convert to the return value type to int.
>>>>
>>>> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
>>>
>>> I don't see this patch make any value.
>>
>> calc_tpm2_event_size return size_t 'size' which derive from u32 'event_field->event_size',
>>
>> convert it to int may result in truncation.
> 
> Two remarks:
> 
> - Your real name is formatted incorrectly. It should be like "Yue Haibig"
>   as shown in [1].
> - If there is no actual regression, this change is useless.

Ok, Thank you.

> 
> [1] https://www.kernel.org/doc/html/v4.17/process/submitting-patches.html
> 
> /Jarkko
> 
> .
> 

Re: [PATCH -next] tpm: change the return type of calc_tpm2_event_size to size_t

[Jason Gunthorpe]

On Tue, Feb 19, 2019 at 12:35:32PM +0200, Jarkko Sakkinen wrote:
> On Tue, Feb 19, 2019 at 05:15:47PM +0800, YueHaibing wrote:
> > On 2019/2/19 16:59, Jarkko Sakkinen wrote:
> > > On Tue, Feb 19, 2019 at 03:26:18PM +0800, YueHaibing wrote:
> > >> calc_tpm2_event_size return size of the event which type is
> > >> size_t, If it is an invalid event, returns 0. And all the
> > >> caller use a size_t variable to check the return value, so
> > >> no need to convert to the return value type to int.
> > >>
> > >> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
> > > 
> > > I don't see this patch make any value.
> > 
> > calc_tpm2_event_size return size_t 'size' which derive from u32 'event_field->event_size',
> > 
> > convert it to int may result in truncation.
> 
> Two remarks:
> 
> - Your real name is formatted incorrectly. It should be like "Yue Haibig"
>   as shown in [1].
> - If there is no actual regression, this change is useless.

Clarity of the code is a laudible goal - not everything is about
fixing bugs or adding features.

It is much easier to write the code properly than to try and prove
that event_size can not exceed INT_MAX.

Jason

Re: [PATCH -next] tpm: change the return type of calc_tpm2_event_size to size_t

[Jarkko Sakkinen]

On Tue, Feb 19, 2019 at 09:34:56AM -0700, Jason Gunthorpe wrote:
> > - Your real name is formatted incorrectly. It should be like "Yue Haibig"
> >   as shown in [1].
> > - If there is no actual regression, this change is useless.
> 
> Clarity of the code is a laudible goal - not everything is about
> fixing bugs or adding features.
> 
> It is much easier to write the code properly than to try and prove
> that event_size can not exceed INT_MAX.

I think it is actually a regression in 4d23cc323cdb.  Should carry a
fixes tag. I did not quite undersand what commit message was saying.
What it should would just

"""
tpm: Fix the type of the return value in calc_tpm2_event_size()

calc_tpm2_event_size() has an invalid signature because it returns a 'size_t'
where as its signature says that it returns 'int'.
"""

Should be also Cc'd to linux-security-module and have cc to stable.

/Jarkko

Re: [PATCH -next] tpm: change the return type of calc_tpm2_event_size to size_t

[YueHaibing]

On 2019/2/20 1:31, Jarkko Sakkinen wrote:
> On Tue, Feb 19, 2019 at 09:34:56AM -0700, Jason Gunthorpe wrote:
>>> - Your real name is formatted incorrectly. It should be like "Yue Haibig"
>>>   as shown in [1].
>>> - If there is no actual regression, this change is useless.
>>
>> Clarity of the code is a laudible goal - not everything is about
>> fixing bugs or adding features.
>>
>> It is much easier to write the code properly than to try and prove
>> that event_size can not exceed INT_MAX.
> 
> I think it is actually a regression in 4d23cc323cdb.  Should carry a
> fixes tag. I did not quite undersand what commit message was saying.
> What it should would just
> 
> """
> tpm: Fix the type of the return value in calc_tpm2_event_size()
> 
> calc_tpm2_event_size() has an invalid signature because it returns a 'size_t'
> where as its signature says that it returns 'int'.
> """
> 
> Should be also Cc'd to linux-security-module and have cc to stable.

Ok, I will fix it in v2.

> 
> /Jarkko
> 
> .
>