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Mon, 28 Jun 2021 11:42:06 -0700 (PDT) MIME-Version: 1.0 References: <20210624112624.31215-1-yee.lee@mediatek.com> <20210624112624.31215-2-yee.lee@mediatek.com> In-Reply-To: <20210624112624.31215-2-yee.lee@mediatek.com> From: Marco Elver Date: Mon, 28 Jun 2021 20:41:55 +0200 Message-ID: Subject: Re: [PATCH v2 1/1] kasan: Add memzero init for unaligned size under SLUB debug To: yee.lee@mediatek.com Cc: andreyknvl@gmail.com, wsd_upstream@mediatek.com, Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Andrew Morton , Matthias Brugger , "open list:KASAN" , "open list:MEMORY MANAGEMENT" , open list , "moderated list:ARM/Mediatek SoC support" , "moderated list:ARM/Mediatek SoC support" Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=google.com header.s=20161025 header.b=vfK499WW; spf=pass (imf06.hostedemail.com: domain of elver@google.com designates 209.85.167.176 as permitted sender) smtp.mailfrom=elver@google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: E628FC021ADC X-Stat-Signature: uc65waugmbnk8i9fzyn4yaes18fk9bxn X-HE-Tag: 1624905727-474849 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, 24 Jun 2021 at 13:27, wrote: > > From: Yee Lee > > Issue: when SLUB debug is on, hwtag kasan_unpoison() would overwrite > the redzone of object with unaligned size. > > An additional memzero_explicit() path is added to replacing init by > hwtag instruction for those unaligned size at SLUB debug mode. > > Signed-off-by: Yee Lee > --- > mm/kasan/kasan.h | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h > index 8f450bc28045..d1054f35838f 100644 > --- a/mm/kasan/kasan.h > +++ b/mm/kasan/kasan.h > @@ -387,6 +387,12 @@ static inline void kasan_unpoison(const void *addr, size_t size, bool init) > > if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK)) > return; > +#if IS_ENABLED(CONFIG_SLUB_DEBUG) Avoid the #if. I think none of the stuff referenced here is only available if CONFIG_SLUB_DEBUG. In that case, please just write: if (IS_ENABLED(CONFIG_SLUB_DEBUG) && init && .........) { The compiler will correctly optimize out the branch if the config option is not enabled. But the benefit is we compile-test this code with all configs. > + if (init && ((unsigned long)size & KASAN_GRANULE_MASK)) { > + init = false; > + memzero_explicit((void *)addr, size); > + } > +#endif Thanks, -- Marco