Re: [PATCH] radix-tree: don't left-shift negative values

[Nicola Vetrini <nicola.vetrini@bugseng.com>]

On 2025-02-13 16:01, Jan Beulich wrote:
> On 13.02.2025 15:52, Nicola Vetrini wrote:
>> On 2025-02-13 15:22, Jan Beulich wrote:
>>> Any (signed) integer is okay to pass into radix_tree_int_to_ptr(), 
>>> yet
>>> left shifting negative values is UB. Use an unsigned intermediate 
>>> type,
>>> reducing the impact to implementation defined behavior (for the
>>> unsigned->signed conversion).
>>> 
>>> Also please Misra C:2012 rule 7.3 by dropping the lower case numeric
>>> 'l'
>>> tag.
>>> 
>>> No difference in generated code, at least on x86.
>>> 
>>> Fixes: b004883e29bb ("Simplify and build-fix (for some gcc versions)
>>> radix_tree_int_to_ptr()")
>>> Reported-by: Teddy Astie <teddy.astie@vates.tech>
>>> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>>> ---
>>> Bugseng: Why was the 7.3 violation not spotted by Eclair? According 
>>> to
>>>          tagging.ecl the codebase is clean for this rule, aiui.
>>> 
>> 
>> radix-tree.{c,h} is out of scope:
>> 
>> automation/eclair_analysis/ECLAIR/out_of_scope.ecl:32:-file_tag+={out_of_scope,"^xen/include/xen/radix-tree\\.h$"}
>> docs/misra/exclude-list.json:153:            "rel_path":
>> "common/radix-tree.c",
> 
> Is there a record of why they are excluded? Is it further explainable
> why exclude-list.json mentions only the .c file and out_of_scope.ecl
> mentions only the .h one? Shouldn't different parts be in sync?
> 

exclude-list.json is used to generate a configuration file for ECLAIR 
just before the analysis starts, so effectively both are excluded. It's 
a good point however to have only one file to handle exclusions, and use 
that file to generate the exclusion list dynamically, but then someone 
might want to exclude certain files only in some analyses and not 
others, which is not a good fit for exclude-list.json as it is now.

@Stefano, thoughts?

Thanks,
  Nicola

>> We are in the process of setting up a wider analysis (i.e. with a
>> different exclusion set) with a broader configuration that may catch
>> these issues.
> 
> Good.
> 
> Jan

-- 
Nicola Vetrini, B.Sc.
Software Engineer
BUGSENG (https://bugseng.com)
LinkedIn: https://www.linkedin.com/in/nicola-vetrini-a42471253