Messages in this thread | | | From | Andrey Konovalov <> | Date | Wed, 29 Nov 2023 04:01:47 +0100 | Subject | Re: [PATCH] fix comparison of unsigned expression < 0 |
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On Wed, Nov 29, 2023 at 2:22 AM Andrew Morton <akpm@linux-foundation.org> wrote: > > On Tue, 28 Nov 2023 15:55:32 +0800 Haibo Li <haibo.li@mediatek.com> wrote: > > > Kernel test robot reported: > > > > ''' > > mm/kasan/report.c:637 kasan_non_canonical_hook() warn: > > unsigned 'addr' is never less than zero. > > ''' > > The KASAN_SHADOW_OFFSET is 0 on loongarch64. > > > > To fix it,check the KASAN_SHADOW_OFFSET before do comparison. > > > > --- a/mm/kasan/report.c > > +++ b/mm/kasan/report.c > > @@ -634,10 +634,10 @@ void kasan_non_canonical_hook(unsigned long addr) > > { > > unsigned long orig_addr; > > const char *bug_type; > > - > > +#if KASAN_SHADOW_OFFSET > 0 > > if (addr < KASAN_SHADOW_OFFSET) > > return; > > - > > +#endif > > We'd rather not add ugly ifdefs for a simple test like this. If we > replace "<" with "<=", does it fix? I suspect that's wrong.
Changing the comparison into "<=" would be wrong.
But I actually don't think we need to fix anything here.
This issue looks quite close to a similar comparison with 0 issue Linus shared his opinion on here:
https://lore.kernel.org/all/Pine.LNX.4.58.0411230958260.20993@ppc970.osdl.org/
I don't know if the common consensus with the regard to issues like that changed since then. But if not, perhaps we can treat this kernel test robot report as a false positive.
Thanks!
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