From: Andrew Morton <akpm@linux-foundation•org>
To: Yury Norov <yury.norov@gmail•com>
Cc: syzbot <syzbot+08ca1fa706a22cc17efe@syzkaller•appspotmail.com>,
linux-kernel@vger•kernel.org, linux-mm@kvack•org,
linux-next@vger•kernel.org, sfr@canb•auug.org.au,
syzkaller-bugs@googlegroups•com,
Andrey Ryabinin <ryabinin.a.a@gmail•com>,
Alexander Potapenko <glider@google•com>,
Andrey Konovalov <andreyknvl@gmail•com>,
Dmitry Vyukov <dvyukov@google•com>,
Vincenzo Frascino <vincenzo.frascino@arm•com>
Subject: Re: [syzbot] linux-next boot error: KASAN: slab-out-of-bounds Read in _find_next_bit
Date: Tue, 6 Sep 2022 22:53:12 -0700 [thread overview]
Message-ID: <20220906225312.263c4493a744cbcb66288283@linux-foundation.org> (raw)
In-Reply-To: <YxfpkzZhJ7GfRuKd@yury-laptop>
On Tue, 6 Sep 2022 17:45:07 -0700 Yury Norov <yury.norov@gmail•com> wrote:
> > > The buggy address belongs to the object at ffff888017576600
> > > which belongs to the cache kmalloc-192 of size 192
> > > The buggy address is located 184 bytes inside of
> > > 192-byte region [ffff888017576600, ffff8880175766c0)
> >
> > At offset 184 of a 192-byte region.
> >
> > So what's wrong with doing that? Does KASAN have an off-by-one?
>
> Hi Andrew, all,
>
> This is a bug in FIND_NEXT_BIT(). It should be
> if (idx >= sz / BITS_PER_LONG) \
> goto out; \
>
> instead of
> if (idx > sz / BITS_PER_LONG) \
> goto out; \
>
> The fix is in bitmap-for-next, expected to be in -next by tomorrow.
> Sorry for the noise.
OK... but why is KASAN reporting a bad access from an area
which appears to be OK?
next prev parent reply other threads:[~2022-09-07 5:53 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-06 13:21 [syzbot] linux-next boot error: KASAN: slab-out-of-bounds Read in _find_next_bit syzbot
2022-09-07 0:31 ` Andrew Morton
2022-09-07 0:45 ` Yury Norov
2022-09-07 5:53 ` Andrew Morton [this message]
2022-09-07 7:17 ` Dmitry Vyukov
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