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* [PATCH] docs: deprecated.rst: Clarify open-coded arithmetic with literals
@ 2021-08-27 17:12 Len Baker
  2021-08-27 19:06 ` Joe Perches
  0 siblings, 1 reply; 4+ messages in thread
From: Len Baker @ 2021-08-27 17:12 UTC (permalink / raw)
  To: Jonathan Corbet, Kees Cook
  Cc: Len Baker, Gustavo A. R. Silva, Joe Perches, linux-doc,
	linux-kernel, linux-hardening

Although using literals for size calculation in allocator arguments may
be harmless due to compiler warnings in case of overflows, it is better
to refactor the code to avoid the use of open-coded math idiom.

So, clarify the preferred way in these cases.

Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Len Baker <len.baker@gmx.com>
---
 Documentation/process/deprecated.rst | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
index 9d83b8db8874..fdfafdefe296 100644
--- a/Documentation/process/deprecated.rst
+++ b/Documentation/process/deprecated.rst
@@ -60,7 +60,8 @@ smaller allocation being made than the caller was expecting. Using those
 allocations could lead to linear overflows of heap memory and other
 misbehaviors. (One exception to this is literal values where the compiler
 can warn if they might overflow. Though using literals for arguments as
-suggested below is also harmless.)
+suggested below is also harmless. So, the preferred way in these cases is
+to refactor the code to keep the open-coded math idiom out.)

 For example, do not use ``count * size`` as an argument, as in::

--
2.25.1


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] docs: deprecated.rst: Clarify open-coded arithmetic with literals
  2021-08-27 17:12 [PATCH] docs: deprecated.rst: Clarify open-coded arithmetic with literals Len Baker
@ 2021-08-27 19:06 ` Joe Perches
  2021-08-27 19:22   ` Gustavo A. R. Silva
  2021-08-29 14:32   ` Len Baker
  0 siblings, 2 replies; 4+ messages in thread
From: Joe Perches @ 2021-08-27 19:06 UTC (permalink / raw)
  To: Len Baker, Jonathan Corbet, Kees Cook
  Cc: Gustavo A. R. Silva, linux-doc, linux-kernel, linux-hardening

On Fri, 2021-08-27 at 19:12 +0200, Len Baker wrote:
> Although using literals for size calculation in allocator arguments may
> be harmless due to compiler warnings in case of overflows, it is better
> to refactor the code to avoid the use of open-coded math idiom.
> 
> So, clarify the preferred way in these cases.
[]
> diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
[]
> @@ -60,7 +60,8 @@ smaller allocation being made than the caller was expecting. Using those
>  allocations could lead to linear overflows of heap memory and other
>  misbehaviors. (One exception to this is literal values where the compiler
>  can warn if they might overflow. Though using literals for arguments as
> -suggested below is also harmless.)
> +suggested below is also harmless. So, the preferred way in these cases is
> +to refactor the code to keep the open-coded math idiom out.)

wordsmithing trivia:

'keep <foo> out' is difficult to parse as 'keep' is generally a positive
word but its meaning is later reversed with out.

'avoid <foo>' maybe be better phrasing.



^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] docs: deprecated.rst: Clarify open-coded arithmetic with literals
  2021-08-27 19:06 ` Joe Perches
@ 2021-08-27 19:22   ` Gustavo A. R. Silva
  2021-08-29 14:32   ` Len Baker
  1 sibling, 0 replies; 4+ messages in thread
From: Gustavo A. R. Silva @ 2021-08-27 19:22 UTC (permalink / raw)
  To: Joe Perches, Len Baker, Jonathan Corbet, Kees Cook
  Cc: Gustavo A. R. Silva, linux-doc, linux-kernel, linux-hardening



On 8/27/21 14:06, Joe Perches wrote:
> On Fri, 2021-08-27 at 19:12 +0200, Len Baker wrote:
>> Although using literals for size calculation in allocator arguments may
>> be harmless due to compiler warnings in case of overflows, it is better
>> to refactor the code to avoid the use of open-coded math idiom.
>>
>> So, clarify the preferred way in these cases.
> []
>> diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
> []
>> @@ -60,7 +60,8 @@ smaller allocation being made than the caller was expecting. Using those
>>  allocations could lead to linear overflows of heap memory and other
>>  misbehaviors. (One exception to this is literal values where the compiler
>>  can warn if they might overflow. Though using literals for arguments as
>> -suggested below is also harmless.)
>> +suggested below is also harmless. So, the preferred way in these cases is
>> +to refactor the code to keep the open-coded math idiom out.)
> 
> wordsmithing trivia:
> 
> 'keep <foo> out' is difficult to parse as 'keep' is generally a positive
> word but its meaning is later reversed with out.
> 
> 'avoid <foo>' maybe be better phrasing.

+1

--
Gustavo

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] docs: deprecated.rst: Clarify open-coded arithmetic with literals
  2021-08-27 19:06 ` Joe Perches
  2021-08-27 19:22   ` Gustavo A. R. Silva
@ 2021-08-29 14:32   ` Len Baker
  1 sibling, 0 replies; 4+ messages in thread
From: Len Baker @ 2021-08-29 14:32 UTC (permalink / raw)
  To: Joe Perches
  Cc: Len Baker, Jonathan Corbet, Kees Cook, Gustavo A. R. Silva,
	linux-doc, linux-kernel, linux-hardening

Hi,

On Fri, Aug 27, 2021 at 12:06:18PM -0700, Joe Perches wrote:
> On Fri, 2021-08-27 at 19:12 +0200, Len Baker wrote:
> > Although using literals for size calculation in allocator arguments may
> > be harmless due to compiler warnings in case of overflows, it is better
> > to refactor the code to avoid the use of open-coded math idiom.
> >
> > So, clarify the preferred way in these cases.
> []
> > diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
> []
> > @@ -60,7 +60,8 @@ smaller allocation being made than the caller was expecting. Using those
> >  allocations could lead to linear overflows of heap memory and other
> >  misbehaviors. (One exception to this is literal values where the compiler
> >  can warn if they might overflow. Though using literals for arguments as
> > -suggested below is also harmless.)
> > +suggested below is also harmless. So, the preferred way in these cases is
> > +to refactor the code to keep the open-coded math idiom out.)
>
> wordsmithing trivia:
>
> 'keep <foo> out' is difficult to parse as 'keep' is generally a positive
> word but its meaning is later reversed with out.
>
> 'avoid <foo>' maybe be better phrasing.
>
Understood. I will do this change and I will send a new version.
Thanks for the review.

Regards,
Len

^ permalink raw reply	[flat|nested] 4+ messages in thread

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2021-08-27 17:12 [PATCH] docs: deprecated.rst: Clarify open-coded arithmetic with literals Len Baker
2021-08-27 19:06 ` Joe Perches
2021-08-27 19:22   ` Gustavo A. R. Silva
2021-08-29 14:32   ` Len Baker

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