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Groups > linux.kernel > #1232092 > unrolled thread

[PATCH] coccinelle: assign signed result to unsigned variable

Started byAndrzej Hajda <a.hajda@samsung.com>
First post2015-09-24 15:00 +0200
Last post2015-10-03 09:10 +0200
Articles 10 on this page of 30 — 3 participants

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  [PATCH] coccinelle: assign signed result to unsigned variable Andrzej Hajda <a.hajda@samsung.com> - 2015-09-24 15:00 +0200
    Re: [PATCH] coccinelle: assign signed result to unsigned variable SF Markus Elfring <elfring@users.sourceforge.net> - 2015-09-24 18:00 +0200
      Re: [PATCH] coccinelle: assign signed result to unsigned variable Andrzej Hajda <a.hajda@samsung.com> - 2015-09-25 12:10 +0200
        Re: [PATCH] coccinelle: assign signed result to unsigned variable SF Markus Elfring <elfring@users.sourceforge.net> - 2015-09-25 18:00 +0200
        Re: [PATCH] coccinelle: assign signed result to unsigned variable SF Markus Elfring <elfring@users.sourceforge.net> - 2015-09-26 09:50 +0200
          Re: [PATCH] coccinelle: assign signed result to unsigned variable Julia Lawall <julia.lawall@lip6.fr> - 2015-09-26 11:10 +0200
            Re: [PATCH] coccinelle: assign signed result to unsigned variable SF Markus Elfring <elfring@users.sourceforge.net> - 2015-09-26 11:50 +0200
              Re: [PATCH] coccinelle: assign signed result to unsigned variable Julia Lawall <julia.lawall@lip6.fr> - 2015-09-26 11:50 +0200
                Re: [PATCH] coccinelle: assign signed result to unsigned variable SF Markus Elfring <elfring@users.sourceforge.net> - 2015-09-26 12:00 +0200
                  Re: [PATCH] coccinelle: assign signed result to unsigned variable Julia Lawall <julia.lawall@lip6.fr> - 2015-09-26 12:00 +0200
                    Re: [PATCH] coccinelle: assign signed result to unsigned variable SF Markus Elfring <elfring@users.sourceforge.net> - 2015-09-26 13:50 +0200
                      Re: [PATCH] coccinelle: assign signed result to unsigned variable Julia Lawall <julia.lawall@lip6.fr> - 2015-09-26 16:00 +0200
                        Re: [PATCH] coccinelle: assign signed result to unsigned variable SF Markus Elfring <elfring@users.sourceforge.net> - 2015-09-26 17:30 +0200
                          Re: [PATCH] coccinelle: assign signed result to unsigned variable Julia Lawall <julia.lawall@lip6.fr> - 2015-09-26 17:40 +0200
                            Re: [PATCH] coccinelle: assign signed result to unsigned variable SF Markus Elfring <elfring@users.sourceforge.net> - 2015-09-26 18:00 +0200
                              Re: [PATCH] coccinelle: assign signed result to unsigned variable Julia Lawall <julia.lawall@lip6.fr> - 2015-09-26 18:00 +0200
                                Re: [PATCH] coccinelle: assign signed result to unsigned variable SF Markus Elfring <elfring@users.sourceforge.net> - 2015-09-26 18:10 +0200
            [PATCH v2] coccinelle: assign signed result to unsigned variable Andrzej Hajda <a.hajda@samsung.com> - 2015-09-28 13:00 +0200
              Re: [PATCH v2] coccinelle: assign signed result to unsigned  variable Julia Lawall <julia.lawall@lip6.fr> - 2015-09-28 13:40 +0200
                Re: [PATCH v2] coccinelle: assign signed result to unsigned variable Andrzej Hajda <a.hajda@samsung.com> - 2015-09-28 14:10 +0200
                  Re: [PATCH v2] coccinelle: assign signed result to unsigned  variable Julia Lawall <julia.lawall@lip6.fr> - 2015-10-01 00:00 +0200
              Re: [PATCH v2] coccinelle: assign signed result to unsigned variable SF Markus Elfring <elfring@users.sourceforge.net> - 2015-09-28 14:10 +0200
                Re: [PATCH v2] coccinelle: assign signed result to unsigned variable Andrzej Hajda <a.hajda@samsung.com> - 2015-09-28 14:20 +0200
                  Re: [PATCH v2] coccinelle: assign signed result to unsigned variable SF Markus Elfring <elfring@users.sourceforge.net> - 2015-09-28 14:30 +0200
                    Re: [Cocci] [PATCH v2] coccinelle: assign signed result to unsigned  variable Julia Lawall <julia.lawall@lip6.fr> - 2015-09-28 14:50 +0200
                      Re: [Cocci] [PATCH v2] coccinelle: assign signed result to unsigned  variable SF Markus Elfring <elfring@users.sourceforge.net> - 2015-09-28 15:00 +0200
                        Re: [Cocci] [PATCH v2] coccinelle: assign signed result to unsigned  variable Julia Lawall <julia.lawall@lip6.fr> - 2015-09-28 15:20 +0200
                          Re: [Cocci] [PATCH v2] coccinelle: assign signed result to unsigned  variable SF Markus Elfring <elfring@users.sourceforge.net> - 2015-09-28 16:00 +0200
                            Re: [Cocci] [PATCH v2] coccinelle: assign signed result to unsigned  variable Julia Lawall <julia.lawall@lip6.fr> - 2015-09-28 17:10 +0200
              Re: [PATCH v2] coccinelle: assign signed result to unsigned  variable Julia Lawall <julia.lawall@lip6.fr> - 2015-10-03 09:10 +0200

Page 2 of 2 — ← Prev page 1 [2]

#1236800 — Re: [PATCH v2] coccinelle: assign signed result to unsigned variable

FromJulia Lawall <julia.lawall@lip6.fr>
Date2015-10-01 00:00 +0200
SubjectRe: [PATCH v2] coccinelle: assign signed result to unsigned variable
Message-ID<qexzQ-LW-1@gated-at.bofh.it>
In reply to#1234072

On Mon, 28 Sep 2015, Andrzej Hajda wrote:

> On 09/28/2015 01:32 PM, Julia Lawall wrote:
> >
> > On Mon, 28 Sep 2015, Andrzej Hajda wrote:
> >
> >> Assigning signed function result to unsigned variable can indicate error.
> >> To decrease number of false positives patch looks if after assignment
> >> there is also check for negative values of the result.
> >>
> >> Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
> >> ---
> >> Hi Julia,
> >>
> >> Thanks for the hint. Now it looks much better.
> >> Summarizing this patch has found 20 problems and has 22 false positives [1][2].
> > Do you have some examples of the false positives?
> ./drivers/acpi/acpica/nsarguments.c:130:1: WARNING: Assigning signed result to
> unsigned variable: required_param_count = METHOD_GET_ARG_COUNT(...)
> ./drivers/char/agp/intel-gtt.c:361:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = KB(...)
> ./drivers/char/agp/intel-gtt.c:364:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = MB(...)
> ./drivers/char/agp/intel-gtt.c:367:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = MB(...)
> ./drivers/char/agp/intel-gtt.c:382:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = MB(...)
> ./drivers/char/agp/intel-gtt.c:385:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = MB(...)
> ./drivers/char/agp/intel-gtt.c:388:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = MB(...)
> ./drivers/char/agp/intel-gtt.c:391:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = MB(...)
> ./drivers/char/agp/intel-gtt.c:394:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = MB(...)
> ./drivers/char/agp/intel-gtt.c:397:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = MB(...)
> ./drivers/char/agp/intel-gtt.c:400:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = MB(...)
> ./drivers/char/agp/intel-gtt.c:403:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = MB(...)
> ./drivers/char/agp/intel-gtt.c:406:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = MB(...)
> ./drivers/char/agp/intel-gtt.c:409:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = MB(...)
> ./drivers/char/agp/intel-gtt.c:412:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = MB(...)
> ./drivers/char/agp/intel-gtt.c:415:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = MB(...)
> ./drivers/char/agp/intel-gtt.c:418:3: WARNING: Assigning signed result to
> unsigned variable: stolen_size = MB(...)
> ./drivers/input/touchscreen/cyttsp4_core.c:967:1: WARNING: Assigning signed
> result to unsigned variable: num_cur_tch = GET_NUM_TOUCHES(...)
> ./drivers/pinctrl/freescale/pinctrl-imx.c:648:2: WARNING: Assigning signed
> result to unsigned variable: nfuncs = of_get_child_count(...)
> ./fs/btrfs/file.c:1572:2: WARNING: Assigning signed result to unsigned variable:
> copied = btrfs_copy_from_user(...)
> ./fs/xfs/libxfs/xfs_inode_fork.c:541:2: WARNING: Assigning signed result to
> unsigned variable: new_size = XFS_BMAP_BROOT_SPACE_CALC(...)
> 
> As you see most of them are macros, of_get_child_count and btrfs_copy_from_user
> return int but always non-negative.

OK, perhaps we could just live with them...

julia
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#1234071 — Re: [PATCH v2] coccinelle: assign signed result to unsigned variable

FromSF Markus Elfring <elfring@users.sourceforge.net>
Date2015-09-28 14:10 +0200
SubjectRe: [PATCH v2] coccinelle: assign signed result to unsigned variable
Message-ID<qdFpL-5fT-9@gated-at.bofh.it>
In reply to#1234048
> +// Options: --include-headers --all-includes

How do you think about the reuse of the parameter "--recursive-includes" here?

Will the list of checked function calls become more complete then?

Regards,
Markus
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#1234074 — Re: [PATCH v2] coccinelle: assign signed result to unsigned variable

FromAndrzej Hajda <a.hajda@samsung.com>
Date2015-09-28 14:20 +0200
SubjectRe: [PATCH v2] coccinelle: assign signed result to unsigned variable
Message-ID<qdFzs-5rF-5@gated-at.bofh.it>
In reply to#1234071
On 09/28/2015 02:07 PM, SF Markus Elfring wrote:
>> +// Options: --include-headers --all-includes
> 
> How do you think about the reuse of the parameter "--recursive-includes" here?

Last time I have tried it, kernel source check took more than 10 hours, so I
gave up.

Regards
Andrzej

> 
> Will the list of checked function calls become more complete then?
> 
> Regards,
> Markus
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#1234077 — Re: [PATCH v2] coccinelle: assign signed result to unsigned variable

FromSF Markus Elfring <elfring@users.sourceforge.net>
Date2015-09-28 14:30 +0200
SubjectRe: [PATCH v2] coccinelle: assign signed result to unsigned variable
Message-ID<qdFJ8-5CT-1@gated-at.bofh.it>
In reply to#1234074
>> How do you think about the reuse of the parameter "--recursive-includes" here?
> 
> Last time I have tried it, kernel source check took more than 10 hours,
> so I gave up.

This is interesting background information.

There are opportunities for more fine-tuning of such a source code analysis,
aren't there?

Regards,
Markus
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#1234111 — Re: [Cocci] [PATCH v2] coccinelle: assign signed result to unsigned variable

FromJulia Lawall <julia.lawall@lip6.fr>
Date2015-09-28 14:50 +0200
SubjectRe: [Cocci] [PATCH v2] coccinelle: assign signed result to unsigned variable
Message-ID<qdG2v-5Zh-39@gated-at.bofh.it>
In reply to#1234077
On Mon, 28 Sep 2015, SF Markus Elfring wrote:

> >> How do you think about the reuse of the parameter "--recursive-includes" here?
> >
> > Last time I have tried it, kernel source check took more than 10 hours,
> > so I gave up.
>
> This is interesting background information.
>
> There are opportunities for more fine-tuning of such a source code analysis,
> aren't there?

I guess parallelism would be helpful?  You could try the following
options:

-j n --chunksize 10 --recursive-includes --include-headers-for-types

where n is the number of cores that you want to use.  Parsed header files
will be cached within chunks.  I don't really know what is the best
chunksize.

julia


>
> Regards,
> Markus
> _______________________________________________
> Cocci mailing list
> Cocci@systeme.lip6.fr
> https://systeme.lip6.fr/mailman/listinfo/cocci
>
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#1234120 — Re: [Cocci] [PATCH v2] coccinelle: assign signed result to unsigned variable

FromSF Markus Elfring <elfring@users.sourceforge.net>
Date2015-09-28 15:00 +0200
SubjectRe: [Cocci] [PATCH v2] coccinelle: assign signed result to unsigned variable
Message-ID<qdGca-6aB-21@gated-at.bofh.it>
In reply to#1234111
> I guess parallelism would be helpful?
> You could try the following options:
> 
> -j n --chunksize 10 --recursive-includes --include-headers-for-types
> 
> where n is the number of cores that you want to use.

Has the make target "coccicheck" direct support for such special parameters?


> Parsed header files will be cached within chunks.

Can the Coccinelle software work together with a kind of "precompiled
header database"?

Regards,
Markus
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#1234139 — Re: [Cocci] [PATCH v2] coccinelle: assign signed result to unsigned variable

FromJulia Lawall <julia.lawall@lip6.fr>
Date2015-09-28 15:20 +0200
SubjectRe: [Cocci] [PATCH v2] coccinelle: assign signed result to unsigned variable
Message-ID<qdGvv-6My-1@gated-at.bofh.it>
In reply to#1234120

On Mon, 28 Sep 2015, SF Markus Elfring wrote:

> > I guess parallelism would be helpful?
> > You could try the following options:
> >
> > -j n --chunksize 10 --recursive-includes --include-headers-for-types
> >
> > where n is the number of cores that you want to use.
>
> Has the make target "coccicheck" direct support for such special parameters?
>
>
> > Parsed header files will be cached within chunks.
>
> Can the Coccinelle software work together with a kind of "precompiled
> header database"?

There is an option --use-cache, which caches the compiled code on the
disk.  But I have not found the effects to be very satisfactory.  It is
still necessary to read in the serialized code.

julia
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#1234175 — Re: [Cocci] [PATCH v2] coccinelle: assign signed result to unsigned variable

FromSF Markus Elfring <elfring@users.sourceforge.net>
Date2015-09-28 16:00 +0200
SubjectRe: [Cocci] [PATCH v2] coccinelle: assign signed result to unsigned variable
Message-ID<qdH8e-1eq-11@gated-at.bofh.it>
In reply to#1234139
>> Can the Coccinelle software work together with a kind of "precompiled
>> header database"?
> 
> There is an option --use-cache, which caches the compiled code
> on the disk.  But I have not found the effects to be very satisfactory.

I am curious if this situation will be improved by further software evolution.

Regards,
Markus
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#1234242 — Re: [Cocci] [PATCH v2] coccinelle: assign signed result to unsigned variable

FromJulia Lawall <julia.lawall@lip6.fr>
Date2015-09-28 17:10 +0200
SubjectRe: [Cocci] [PATCH v2] coccinelle: assign signed result to unsigned variable
Message-ID<qdIdY-301-23@gated-at.bofh.it>
In reply to#1234175
On Mon, 28 Sep 2015, SF Markus Elfring wrote:

> >> Can the Coccinelle software work together with a kind of "precompiled
> >> header database"?
> >
> > There is an option --use-cache, which caches the compiled code
> > on the disk.  But I have not found the effects to be very satisfactory.
>
> I am curious if this situation will be improved by further software evolution.

There are no plans in that direction.

julia
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#1238748 — Re: [PATCH v2] coccinelle: assign signed result to unsigned variable

FromJulia Lawall <julia.lawall@lip6.fr>
Date2015-10-03 09:10 +0200
SubjectRe: [PATCH v2] coccinelle: assign signed result to unsigned variable
Message-ID<qfp7b-36r-3@gated-at.bofh.it>
In reply to#1234048
Some comments:

If you get 20 good results and 22 false positives, I'm not sure whether 
high confidence is justified.  That seemes more like moderate confidence.

On the other hand, I think it is possible to get rid of the false 
positives.  The false positives are coming from the fact that you have:

if ( \( vu < 0 \| vu <= 0 \) ) S1 else S2

This can be flipped around to

if ( ! \( vu < 0 \| vu <= 0 \) ) S2 else S1

and then when we propagate the ! into the disjunction, we get v >= 0 for 
the first condition and v > 0 for the second condition.  v >= 0 is always 
true, so it could be reasonable to highlight it, but v > 0 is a perfectly 
reasonable test for an unsigned value, and is where you are getting the 
false positives from.  If you want to get rid of both v >= 0 and v < 0 
then you can just put disable neg_if in the initial @@, just after r, ie

@r disable neg_if@

On the other hand, if you want to keep the warning on v >= 0 but drop the 
warning on v > 0, then you will have to split the rules and put the 
disable neg_if on the one for v <= 0.

I think it would also be reasonable to merge the proposed semantic 
patches.  I guess this one gives most of the results anyway?

With recursive_includes, I got 70 results, at least 20 of which should be 
false positives due to the MB case.

julia
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