Re: [PATCH v5 1/7] string: Add strprefix(), and deprecate str_has_prefix()

[Alejandro Colomar <alx@kernel.org>]

[-- Attachment #1: Type: text/plain, Size: 1979 bytes --]

Hi Andy,

> Date: 2026-11-13 16:34:13+0200
> From: Andy Shevchenko <andriy.shevchenko@intel.com>
>
> On Fri, Nov 13, 2026 at 04:33:37PM +0200, Andy Shevchenko wrote:
> > On Fri, Nov 13, 2026 at 02:10:29PM +0100, Alejandro Colomar wrote:
> > > As Bartosz reported, str_has_prefix() has a bug: it can't differentiate
> > > between an empty prefix matching an empty string from a non-matching
> > > prefix.  This is a fundamental design flaw in this API, and not
> > > something that can be fixed.
> > > 
> > > As always, this is a consequence of choosing sizes instead of pointers.
> > > Sizes are often the wrong choice.  In this specific case, pointers are
> > > more capable of differentiating these cases, as NULL is a special
> > > sentinel value that doesn't need to overload a valid value.
> > > 
> > > Let's implement strprefix(), a function that returns a pointer
> > > right after the prefix if found, and a null pointer if not found.
> > > 
> > > We'll slowly migrate existing code from str_has_prefix() to strprefix().
> > > 
> > > Move the description from str_has_prefix(), and describe
> > > str_has_prefix() by comparing it to strprefix().
> > > 
> > > Reported-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
> > > Link: https://lore.kernel.org/linux-hardening/20261104-fwnode-for-each-prop-v1-1-6e28fe1c72c4@oss.qualcomm.com/
> 
> > It's unreferred Link tag, spurious? Please, refer to it in the commit message
> > to understand why it's here. Use Link: $URL [1] and use [1] in the text.
> 
> Ah, perhaps you wanted Closes tag instead?

Yeah, it was for linking to Bart's report.  BTW, is it okay to have two
consecutive patches with the same Closes tag?  I guess it is, because
they close different aspects of the same issue.  But at the same time,
the first one doesn't fully close the link.  I guess yeah, I should just
put it in both.  Thanks!


Cheers,
Alex

-- 
<https://www.alejandro-colomar.es>

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]