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Subject: Re: [PATCH v2 18/33] lib/string: Add KMSAN support to strlcpy() and
 strlcat()
From:   Ilya Leoshkevich <iii@linux.ibm.com>
To:     Alexander Potapenko <glider@google.com>
Cc:     Alexander Gordeev <agordeev@linux.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Heiko Carstens <hca@linux.ibm.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Marco Elver <elver@google.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Pekka Enberg <penberg@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Hyeonggon Yoo <42.hyeyoo@gmail.com>,
        kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-s390@vger.kernel.org,
        linux-trace-kernel@vger.kernel.org,
        Mark Rutland <mark.rutland@arm.com>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Sven Schnelle <svens@linux.ibm.com>
Date:   Wed, 13 Dec 2023 01:53:51 +0100
In-Reply-To: <CAG_fn=XQkhecLYFmJugOG+GawvDQ5Xsj5fTRbOAhU8Z5CfsjPA@mail.gmail.com>
References: <20231121220155.1217090-1-iii@linux.ibm.com>
         <20231121220155.1217090-19-iii@linux.ibm.com>
         <CAG_fn=XQkhecLYFmJugOG+GawvDQ5Xsj5fTRbOAhU8Z5CfsjPA@mail.gmail.com>
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On Fri, 2023-12-08 at 17:50 +0100, Alexander Potapenko wrote:
> On Tue, Nov 21, 2023 at 11:02=E2=80=AFPM Ilya Leoshkevich <iii@linux.ibm.=
com>
> wrote:
> >=20
> > Currently KMSAN does not fully propagate metadata in strlcpy() and
> > strlcat(), because they are built with -ffreestanding and call
> > memcpy(). In this combination memcpy() calls are not instrumented.
>=20
> Is this something specific to s390?

Nice catch - I can't reproduce this behavior anymore. Even if I go
back to the clang version that first introduced KMSAN on s390x, the
memset() instrumentation with -ffreestanding is still there. I should
have written down more detailed notes after investigating this, but
here we are. I will drop this patch as well as 10/33.

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