Re: [PATCH 0/6] bitmap: fix three parsing bugs in bitmap_parse() and bitmap_parselist()

From: Andrew Morton

Date: Fri Sep 25 2026 - 16:40:24 EST


On Fri, 25 Sep 2026 13:05:06 -0400 Yury Norov <ynorov@xxxxxxxxxx> wrote:

> On Fri, Sep 25, 2026 at 03:53:01PM +0530, shashank wrote:
> > This series fixes three cases where the bitmap string parsers accept
> > input they are documented to reject, or produce a different mask than
> > the one requested. Each fix is followed by a patch adding the failing
> > cases to lib/test_bitmap.c.
> >
> > 1-2: bitmap_parse() treats a non-hex character directly before a chunk
> > of exactly eight hex digits as a separator, so "x12345678" and
> > "0x0000000f" are accepted while "0xf" is rejected. This is a
> > regression from the bitmap_parse() rework; the old __bitmap_parse()
> > rejected all of them.
> >
> > 3-4: bitmap_parselist() does not check for the end of the region after
> > the group size of a "range:used/group" region, so since N and
> > all became valid region starts, "0-7:1/2N" or "0-7:1/2all" are
> > silently parsed as two regions.
> >
> > 5-6: bitmap_parselist() walks a "range:used/group" region with an
> > unsigned int that wraps around when the group size is close to
> > UINT_MAX, setting bits below the requested range. This needs an
> > absurd group size and never writes out of bounds.
> >
> > With the series applied, test_bitmap reports "all 391544 tests passed"
> > (UML, x86_64). The three fixes are independent and can be applied in
> > any order.
>
> That looks reasonable, but please resend the series with your full
> real name, and also specify the version of LLM you've used to prepare
> the series. I'm uncomfortable taking anonymous commitments.

fyi, this was changed by 816d9992d9ed ("coding-assistants: simplify
attribution") - see latest Documentation/process/coding-assistants.rst.

So now everything is supposed to say only "Assisted-by: LLM". I find
this regrettable - I'm interested in seeing what people are using. Oh
well.