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Thu, 21 Mar 2024 05:29:16 -0700 (PDT) MIME-Version: 1.0 References: <20240320101851.2589698-1-glider@google.com> <20240320101851.2589698-2-glider@google.com> In-Reply-To: <20240320101851.2589698-2-glider@google.com> From: Marco Elver Date: Thu, 21 Mar 2024 13:28:40 +0100 Message-ID: Subject: Re: [PATCH v2 2/3] instrumented.h: add instrument_memcpy_before, instrument_memcpy_after To: Alexander Potapenko Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com, tglx@linutronix.de, x86@kernel.org, Dmitry Vyukov , Tetsuo Handa , Linus Torvalds Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: A9BA91C002A X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: e8m4kw415zanqr14h9qru7ab3dreea41 X-HE-Tag: 1711024157-633563 X-HE-Meta: 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 rUUB00zv jTJDP19WQiYVa7H1V3+RlelD+TgZp/aeFFL0pyNoQENMpc/xDSHwQ0K3Beqm11yh5MKB2HkYOk9teTkDd+Hi+RE9KeWbDkRPU2fFB11/ky6U3qXAGFy83n3WALtQiB85zaGzmpc8C0si9DAF7xT5I52rTTT6fOeGgU3tjDcErOKYK1AUu7WoZCoIBh+t7KpNG9Vig8bJcqhUIVbubyMY96G1El920pnsgKgJRUIgXuv8I+1JtFXS04EBvzkRrhDgA6SED339aaqfoA3GUjvD8NcLJnHT9c76pAA1j7FGaS+0n58WkqCePbdTdRQZZTPrhQWpwnUTwoRO+O2h3+XiSInDpkP+/+E1isS29tSlLXDFSRwrQMepmSUXg8dNjIolayEGPVUZX8srj6+bYsbEaw6F3Bp8tL6egM04e 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: List-Subscribe: List-Unsubscribe: On Wed, 20 Mar 2024 at 11:19, Alexander Potapenko wrote: > > Bug detection tools based on compiler instrumentation may miss memory > accesses in custom memcpy implementations (such as copy_mc_to_kernel). > Provide instrumentation hooks that tell KASAN, KCSAN, and KMSAN about > such accesses. > > Link: https://lore.kernel.org/all/3b7dbd88-0861-4638-b2d2-911c97a4cadf@I-love.SAKURA.ne.jp/ > Signed-off-by: Alexander Potapenko > Cc: Dmitry Vyukov > Cc: Marco Elver > Cc: Tetsuo Handa > Cc: Linus Torvalds Reviewed-by: Marco Elver > --- > v2: fix a copypasto in a comment spotted by Linus > --- > include/linux/instrumented.h | 35 +++++++++++++++++++++++++++++++++++ > 1 file changed, 35 insertions(+) > > diff --git a/include/linux/instrumented.h b/include/linux/instrumented.h > index 1b608e00290aa..711a1f0d1a735 100644 > --- a/include/linux/instrumented.h > +++ b/include/linux/instrumented.h > @@ -147,6 +147,41 @@ instrument_copy_from_user_after(const void *to, const void __user *from, > kmsan_unpoison_memory(to, n - left); > } > > +/** > + * instrument_memcpy_before - add instrumentation before non-instrumented memcpy > + * @to: destination address > + * @from: source address > + * @n: number of bytes to copy > + * > + * Instrument memory accesses that happen in custom memcpy implementations. The > + * instrumentation should be inserted before the memcpy call. > + */ > +static __always_inline void instrument_memcpy_before(void *to, const void *from, > + unsigned long n) > +{ > + kasan_check_write(to, n); > + kasan_check_read(from, n); > + kcsan_check_write(to, n); > + kcsan_check_read(from, n); > +} > + > +/** > + * instrument_memcpy_after - add instrumentation after non-instrumented memcpy > + * @to: destination address > + * @from: source address > + * @n: number of bytes to copy > + * @left: number of bytes not copied (if known) > + * > + * Instrument memory accesses that happen in custom memcpy implementations. The > + * instrumentation should be inserted after the memcpy call. > + */ > +static __always_inline void instrument_memcpy_after(void *to, const void *from, > + unsigned long n, > + unsigned long left) > +{ > + kmsan_memmove(to, from, n - left); > +} > + > /** > * instrument_get_user() - add instrumentation to get_user()-like macros > * @to: destination variable, may not be address-taken > -- > 2.44.0.291.gc1ea87d7ee-goog >